Compare (5×3)² and Reciprocal of (4×4)⁻²: Insert > < or =

Exponent Rules with Negative Powers

Insert the compatible sign:

>,<,= >,<,=

(5×3)21(4×4)2 (5\times3)^2\Box\frac{1}{\left(4\times4\right)^{-2}}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Choose the appropriate sign
00:06 First let's simplify the left side
00:15 Let's calculate the multiplication
00:19 Now let's simplify the right side
00:30 Let's calculate the multiplication
00:34 Let's use the negative exponent formula
00:38 Any number (A) with a negative exponent(-N)
00:42 Equals the reciprocal number (1\A) with the opposite exponent (N)
00:45 Let's use this formula in our exercise
00:48 Let's substitute the reciprocal number and the opposite exponent
00:56 And this is the simplification for the right side
01:11 Now let's compare the simplifications and see which one is larger
01:20 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Insert the compatible sign:

>,<,= >,<,=

(5×3)21(4×4)2 (5\times3)^2\Box\frac{1}{\left(4\times4\right)^{-2}}

2

Step-by-step solution

To solve this problem, let's evaluate each expression separately and then compare them:

Step 1: Evaluate (5×3)2(5 \times 3)^2

  • Calculate 5×35 \times 3:
5×3=15 5 \times 3 = 15
  • Now, square 15:
152=225 15^2 = 225

Step 2: Evaluate 1(4×4)2\frac{1}{(4 \times 4)^{-2}}

  • Calculate 4×44 \times 4:
4×4=16 4 \times 4 = 16
  • Apply the negative exponent rule: an=1ana^{-n} = \frac{1}{a^n}. Thus, 162=116216^{-2} = \frac{1}{16^2}.
  • Calculate 16216^2:
162=256 16^2 = 256
  • Then, take the reciprocal as indicated by the negative exponent:
1162=11256=256 \frac{1}{16^{-2}} = \frac{1}{\frac{1}{256}} = 256

Step 3: Compare the two results

  • We have (5×3)2=225(5 \times 3)^2 = 225 and 1(4×4)2=256\frac{1}{(4 \times 4)^{-2}} = 256.
  • Compare these values: 225<256225 \lt 256.

The correct sign to place between the expressions is <<. Thus, the solution to the problem is:

(5×3)2<1(4×4)2 (5 \times 3)^2 \lt \frac{1}{(4 \times 4)^{-2}}

Therefore, the correct answer is <\boxed{\lt}.

3

Final Answer

<

Key Points to Remember

Essential concepts to master this topic
  • Negative Exponent Rule: an=1an a^{-n} = \frac{1}{a^n} transforms negative powers to fractions
  • Reciprocal Property: 1xn=xn \frac{1}{x^{-n}} = x^n , so 1162=162=256 \frac{1}{16^{-2}} = 16^2 = 256
  • Check Work: Calculate each side separately then compare: 225 < 256 ✓

Common Mistakes

Avoid these frequent errors
  • Confusing reciprocals with negative exponents
    Don't treat 1(4×4)2 \frac{1}{(4×4)^{-2}} as 1256 \frac{1}{256} = 0.004! This ignores that the negative exponent already creates a reciprocal. Always remember: 1an=an \frac{1}{a^{-n}} = a^n , so the reciprocal of a reciprocal gives you the original power.

Practice Quiz

Test your knowledge with interactive questions

\( 112^0=\text{?} \)

FAQ

Everything you need to know about this question

Why does 1162 \frac{1}{16^{-2}} become 256 instead of a tiny fraction?

+

Great question! Since 162=1162=1256 16^{-2} = \frac{1}{16^2} = \frac{1}{256} , taking the reciprocal gives us 11256=256 \frac{1}{\frac{1}{256}} = 256 . The reciprocal of a reciprocal brings you back to the original!

How do I remember the negative exponent rule?

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Think of it as "flip and drop the negative": 53 5^{-3} becomes 153 \frac{1}{5^3} . The negative sign means "put it in the denominator" and make the exponent positive.

Should I always convert negative exponents first?

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Yes! It's much easier to work with positive exponents. Convert an a^{-n} to 1an \frac{1}{a^n} early in your solution to avoid confusion later.

What if I calculated (5×3)² as 5²×3² = 25×9 = 225?

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Perfect! That's absolutely correct. You can either calculate (5×3)2=152=225 (5×3)^2 = 15^2 = 225 or use the power rule: (5×3)2=52×32=25×9=225 (5×3)^2 = 5^2 × 3^2 = 25 × 9 = 225 . Both methods work!

How do I compare 225 and 256 quickly?

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Since both are perfect squares, you can think: 225=152 225 = 15^2 and 256=162 256 = 16^2 . Since 15 < 16, we know 152<162 15^2 < 16^2 , so 225 < 256.

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