Examples with solutions for Applying Combined Exponents Rules: Identify the greater value

Exercise #1

Which value is greater?

Video Solution

Step-by-Step Solution

To solve this problem, we need to simplify and compare the given expressions.

Let's simplify each:

  • y7×y2 y^7 \times y^2 :
    Using the product of powers rule, y7×y2=y7+2=y9 y^7 \times y^2 = y^{7+2} = y^9 .
  • (y4)3 (y^4)^3 :
    Using the power of a power rule, (y4)3=y4×3=y12 (y^4)^3 = y^{4 \times 3} = y^{12} .
  • y9 y^9 :
    This is already in its simplest form, y9 y^9 .
  • y11y4 \frac{y^{11}}{y^4} :
    Using the power of a quotient rule, y11y4=y114=y7 \frac{y^{11}}{y^4} = y^{11-4} = y^7 .

Now that all the expressions are in the form yn y^n , we can compare the exponents to see which is greatest: y9y^9, y12y^{12}, y9y^9, and y7y^7.

The expression with the highest power is y12 y^{12} , which corresponds to the choice (y4)3 (y^4)^3 .

Thus, the greater value among the choices is (y4)3 (y^4)^3 .

Answer

(y4)3 (y^4)^3

Exercise #2

Which value is greater?

Video Solution

Step-by-Step Solution

To determine which value is greater, let's simplify each choice:

Choice 1: (a2)4 (a^2)^4
By using the power of a power rule: (xm)n=xm×n (x^m)^n = x^{m \times n} , it simplifies to:
(a2)4=a2×4=a8 (a^2)^4 = a^{2 \times 4} = a^8 .

Choice 2: a2+a0 a^2 + a^0
Evaluate using the zero exponent rule, a0=1 a^0 = 1 :
This expression becomes a2+1 a^2 + 1 .

Choice 3: a2×a1 a^2 \times a^1
Apply the product of powers rule: xm×xn=xm+n x^m \times x^n = x^{m+n} :
This simplifies to a2+1=a3 a^{2+1} = a^3 .

Choice 4: a14a9 \frac{a^{14}}{a^9}
Apply the quotient of powers rule: xmxn=xmn \frac{x^m}{x^n} = x^{m-n} :
This simplifies to a149=a5 a^{14-9} = a^5 .

Now, let's compare these simplified forms:
We have a8 a^8 , a2+1 a^2 + 1 , a3 a^3 , and a5 a^5 .

For a>1 a > 1 , exponential functions grow rapidly, thus:
- a8 a^8 is greater than a5 a^5 .
- a8 a^8 is greater than a3 a^3 .
- a8 a^8 is greater than a2+1 a^2 + 1 for sufficiently large aa.

Thus, the expression with the highest power, and therefore the greatest value, is (a2)4 (a^2)^4 .

Answer

(a2)4 (a^2)^4

Exercise #3

Which value is greater?

Video Solution

Step-by-Step Solution

To determine which of the given expressions is the greatest, we will use the relevant exponent rules to simplify each one:

  • Simplify y7×y2 y^7 \times y^2 :
    Using the Product of Powers rule, we have y7×y2=y7+2=y9 y^7 \times y^2 = y^{7+2} = y^9 .
  • Simplify (y4)3 (y^4)^3 :
    Using the Power of a Power rule, we have (y4)3=y4×3=y12 (y^4)^3 = y^{4 \times 3} = y^{12} .
  • Simplify y9 y^9 :
    This expression is already simplified and is y9 y^9 .
  • Simplify y11y4 \frac{y^{11}}{y^4} :
    Using the Division of Powers rule, we have y11y4=y114=y7 \frac{y^{11}}{y^4} = y^{11-4} = y^7 .

After simplifying, we compare the powers of y y from each expression:

  • y9 y^9 from y7×y2 y^7 \times y^2
  • y12 y^{12} from (y4)3 (y^4)^3
  • y9 y^9 from y9 y^9
  • y7 y^7 from y11y4 \frac{y^{11}}{y^4}

Clearly, y12 y^{12} is the largest power among the expressions, meaning that (y4)3 (y^4)^3 is the greatest value.

Therefore, the correct choice is (y4)3 (y^4)^3 .

Answer

(y4)3 (y^4)^3

Exercise #4

Which value is greater?

Video Solution

Step-by-Step Solution

To determine which expression has the greatest value, we apply the exponent rules to simplify each choice:

  • For x3×x4 x^3 \times x^4 , using the product rule: x3×x4=x3+4=x7 x^3 \times x^4 = x^{3+4} = x^7 .
  • For (x3)5 (x^3)^5 , using the power of a power rule: (x3)5=x3×5=x15 (x^3)^5 = x^{3 \times 5} = x^{15} .
  • x10 x^{10} is already in its simplest form.
  • For x9x2 \frac{x^9}{x^2} , using the quotient rule: x9x2=x92=x7 \frac{x^9}{x^2} = x^{9-2} = x^7 .

To identify the greater value, we compare the exponents:

  • x7 x^7 from choices 1 and 4.
  • x15 x^{15} from choice 2.
  • x10 x^{10} from choice 3.

The expression with the largest exponent is (x3)5 (x^3)^5 or x15 x^{15} .

Therefore, the expression with the greatest value is (x3)5(x^3)^5.

Answer

(x3)5 (x^3)^5

Exercise #5

x4x8x3x4——x10x3x5 \frac{x^4x^8x^{-3}}{x^{-4}}_{——}\frac{x^{10}x^3}{x^5}

Video Solution

Step-by-Step Solution

To solve the problem, follow these steps to simplify both expressions using exponent rules:

First Expression: x4x8x3x4\frac{x^4 x^8 x^{-3}}{x^{-4}}

  • Combine the exponents in the numerator: x4+83=x9x^{4+8-3} = x^9.
  • Apply the quotient rule: x9x4=x9(4)=x9+4=x13\frac{x^9}{x^{-4}} = x^{9 - (-4)} = x^{9 + 4} = x^{13}.

Second Expression: x10x3x5\frac{x^{10} x^3}{x^5}

  • Combine the exponents in the numerator: x10+3=x13x^{10+3} = x^{13}.
  • Apply the quotient rule: x13x5=x135=x8\frac{x^{13}}{x^5} = x^{13-5} = x^8.

Now we compare the results:
First Expression: x13x^{13}
Second Expression: x8x^8

In general, x13x^{13} is larger than x8x^8 for positive x x , but since xx could be any real number not zero, the full comparison could vary for negative xx.
Therefore, given the context, it's difficult to calculate a single universal answer without more information on the value of xx.

Thus, it is not possible to calculate universally between these expressions.

Therefore, our answer is Choice 4: It is not possible to calculate.

Answer

It is not possible to calculate

Exercise #6

If:

a>0, \hspace{8pt}b>1

Fill in the blank:

(ab)7b8 —— b4(ba)7 (\frac{a}{b})^{-7}\cdot b^8\text{ }_{——\text{ }}b^{-4}\cdot(\frac{b}{a})^7

Video Solution

Step-by-Step Solution

In this problem, we are asked to determine whether it's an equality or an inequality, and if it's an inequality - what is its direction?

To do this, we will first use the law of exponents for negative exponents:

xn=1xn x^{-n}=\frac{1}{x^n} Before we start solving the problem, let's understand this law in a slightly different way:

Note that if we treat this law as an equation (in fact it is an equation in every sense), and multiply both sides of the equation by the common denominator which is:

xn x^n We get:

xn=1xnxn1=1xn/xnxnxn=1 x^{-n}=\frac{1}{x^n}\\ \frac{x^n}{1} =\frac{1}{x^n}\hspace{8pt} \text{/}\cdot x^n\\ x^n\cdot x^{-n}=1 In the first part we recall that any number can be represented as itself divided by 1. We apply this to the left side of the equation, then we multiply by the common denominator.

To know by how much we need to multiply each numerator (after reduction with the common denominator) we ask the question "By how much did we multiply the current denominator to get the common denominator?".

Let's see the result we got:

xnxn=1 x^n\cdot x^{-n}=1 Meaning that xn,xn x^n,\hspace{4pt}x^{-n} are reciprocal numbers to each other, or in other words:

xn x^n is reciprocal to xn x^{-n} (and vice versa),

And in particular:

x,x1 x,\hspace{4pt}x^{-1} are reciprocal to each other,

We can apply this understanding to the problem if we also remember the fact that the reciprocal of a fraction is the number we get by swapping the numerator and denominator, meaning that the fractions:

zw,wz \frac{z}{w},\hspace{4pt}\frac{w}{z} are reciprocal fractions to each other - which can be understood logically, as their multiplication will clearly give the result 1.

And if we combine this with the previous understanding, we can easily conclude that:

(zw)1=wz \big(\frac{z}{w}\big)^{-1}=\frac{w}{z} Meaning that raising a fraction to the power of negative one will give us the reciprocal fraction, obtained by swapping the numerator and denominator.

Let's return to the problem and apply these understandings, in addition we'll recall the law of multiplying exponents, but in the opposite direction:

(zm)n=zmn (z^m)^n=z^{m\cdot n}

We'll also apply this law to the problem, we'll first deal with the left term:

(ab)7b8 \big(\frac{a}{b}\big)^{-7}\cdot b^8 We'll start with the first term in the expression:

(ab)7=(ab)17=((ab)1)7 \big(\frac{a}{b}\big)^{-7}= \big (\frac{a}{b} \big )^{-1\cdot 7}= \big (\big (\frac{a}{b}\big )^{-1} \big )^{7} In the first part we present the exponent expression as a multiplication between two numbers, in the second part we apply the law of multiplying exponents in its opposite direction.

Next, we'll apply the understanding that raising a fraction to the power of negative one will always give the reciprocal fraction, obtained by swapping the numerator with the denominator: we'll apply this to the first term in the expression we got in the last part:

((ab)1)7=(ba)7 \big (\big (\frac{a}{b}\big )^{-1} \big )^{7} = \big (\frac{b}{a} \big )^{7} Let's summarize. We got that:

(ab)7b8=((ab)1)7b8=(ba)7b8 \big(\frac{a}{b}\big)^{-7}\cdot b^8 = \big (\big (\frac{a}{b}\big )^{-1} \big )^{7}\cdot b^8= \big (\frac{b}{a} \big )^{7} \cdot b^8

Now let's return to the problem and examine what we have:

(ba)7b8 — (ba)7b4 \big (\frac{b}{a} \big )^{7} \cdot b^8 \text{ }_{—\text{ }}\big(\frac{b}{a}\big)^7 \cdot b^{-4} We use the distributive property and rearrange the right-side expression.

Note that, on both sides, the first expression (i.e., the fraction with the exponent) is identical. However, the second term in the multiplication is different on both sides, and this is because it's given that:

b>1 (If it could also be equal to one, we could argue that maybe these terms could be equal, but it's given that it's greater than one and therefore these terms are certainly different).

Therefore we can conclude that this is not an equality but an inequality, and we need to determine its direction.

Next, let's note that since it's also given that:

a>0 We can conclude that:

\big (\frac{b}{a} \big )^{7} >0 And this is because both the numerator of the fraction and the denominator of the fraction are positive numbers,

And therefore the direction of the inequality is not dependent on this term, (if we didn't know the sign of this term for certain, we wouldn't be able to determine the direction of the inequality later on)

Meaning-

The term that will determine the direction of the inequality is the second term in the multiplication on both sides, meaning- we need to find the direction between the terms:

b8 — b4 b^8 \text{ }_{—\text{ }}b^{-4} We keep the original sides these terms were on.

It will be enough to answer the given problem.

For this, we'll remember the rules of inequality for exponential expressions, which simply state that the direction of inequality between exponential expressions with equal bases will be determined both by the value of the bases and by the exponents in the following way:

For a base greater than one, the direction of inequality between the exponential expressions will maintain the direction of inequality between the exponents, meaning- for a base: x x , such that:

x>1 (The base is always defined to be a positive number)

And exponents z,w z,\hspace{4pt}w such that: z>w It holds that:

x^z>x^w

And for a base smaller than 1 and greater than 0, the direction of inequality between the exponential expressions will be opposite to the direction of inequality between the exponents, meaning- for a base: x x , such that:

1 >x>0 (The base is always defined to be a positive number)

And exponents z,w z,\hspace{4pt}w such that: z>w It holds that:

x^w >x^z

Let's return then to the problem:

We are required to determine the direction of inequality between the expressions:

b8 — b4 b^8 \text{ }_{—\text{ }}b^{-4} From what's given in the problem b>1 Meaning greater than one, and therefore the direction of inequality between the expressions will be the same as the direction of inequality that between the exponents.

Therefore, we'll examine the exponents of the expressions in question here.

Since it's clear that:

8>-4 Then it holds that:

b^8 \text{ }>{\text{ }}b^{-4}

And therefore the correct answer is answer B.

Answer

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Exercise #7

222324 — 232225 2^2\cdot2^{-3}\cdot2^4\text{ }_{—\text{ }}2^3\cdot2^{-2}\cdot2^5

Video Solution

Answer

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Exercise #8

74 —— 78 7^{-4}\text{ }_{——\text{ }}7^{-8}

Video Solution

Answer

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Exercise #9

727873(7)4——727973(7)4 \frac{7^2\cdot7^{-8}}{7^3\cdot(-7)^4}_{——}\frac{7^2\cdot7^{-9}}{7^3\cdot(-7)^4}

Video Solution

Answer

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Exercise #10

a41a——b5b12 a^4\frac{1}{a}_{——}b^5\cdot b^{-12}

Video Solution

Answer

It is not possible to calculate