Simplify (-3)⁵ × 8⁴ Divided by Multiple Powers of -3

Question

(3)584(3)3(3)2(3)5=? \frac{(-3)^5\cdot8^4}{(-3)^3(-3)^2(-3)^{-5}}=\text{?}

Video Solution

Solution Steps

00:00 Simply
00:09 When multiplying powers with equal bases
00:12 The power of the result equals the sum of powers
00:16 We'll use this formula in our exercise, we'll sum the powers
00:29 Let's calculate the power
00:34 According to power laws, any number to the power of 0 equals 1
00:37 As long as the number is not 0
00:41 We'll use this formula in our exercise
00:45 Any number to the power of 1 equals the number itself
00:55 We'll break down minus 3 into factors of minus and 3
01:03 When we have a power of a multiplication of several terms
01:07 Each factor will be raised to the power
01:10 We'll use this formula in our exercise
01:23 We'll break down the negative power, and we'll be left with minus
01:39 And this is the solution to the question

Step-by-Step Solution

First, let's recall the law of exponents for multiplication between terms with identical bases:

aman=am+n a^m\cdot a^n=a^{m+n}

and we'll use it to handle the fraction's denominator in the problem:

(3)584(3)3(3)2(3)5=(3)584(3)3+2+(5)=(3)584(3)0 \frac{(-3)^5\cdot8^4}{(-3)^3(-3)^2(-3)^{-5}}=\frac{(-3)^5\cdot8^4}{(-3)^{3+2+(-5)}}=\frac{(-3)^5\cdot8^4}{(-3)^0}

where in the first stage we'll apply the above law to the denominator and then simplify the expression with the exponent in the denominator,

Now let's remember that raising any number to the power of 0 gives the result 1, or mathematically:

X0=1 X^0=1

therefore the denominator we got in the last stage is 1,

meaning we got that:

(3)584(3)3(3)2(3)5=(3)584(3)0=(3)5841=(3)584 \frac{(-3)^5\cdot8^4}{(-3)^3(-3)^2(-3)^{-5}}=\frac{(-3)^5\cdot8^4}{(-3)^0}=\frac{(-3)^5\cdot8^4}{1}=(-3)^5\cdot8^4

Now let's recall the law of exponents for an exponent of a product in parentheses:

(xy)n=xnyn (x\cdot y)^n=x^n\cdot y^n

and we'll apply this law to the first term in the product we got:

(3)584=(13)584=(1)53584=13584=3584 (-3)^5\cdot8^4=(-1\cdot3)^5\cdot8^4 =(-1)^5\cdot3^5\cdot8^4=-1\cdot 3^5\cdot 8^4=-3^5\cdot8^4

Note that the exponent applies separately to both the number 3 and its sign, which is the minus sign that is actually multiplication by 1 -1

Let's summarize everything we did, we got that:

(3)584(3)3(3)2(3)5=(3)584=3584 \frac{(-3)^5\cdot8^4}{(-3)^3(-3)^2(-3)^{-5}}=(-3)^5\cdot8^4 = -3^5\cdot8^4

Therefore the correct answer is answer C.

Answer

3584 -3^5\cdot8^4