Compare Powers: (10×3)^7 and the Reciprocal of (15×2)^-7

Question

Insert the compatible sign:

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(10×3)71(15×2)7 (10\times3)^7\Box\frac{1}{\left(15\times2\right)^{-7}}

Video Solution

Solution Steps

00:00 Insert the appropriate sign
00:04 According to the laws of exponents, a number to the power (N)
00:07 equals the reciprocal number to the power multiplied by (-1)
00:14 Let's apply this formula to our exercise
00:19 Convert to the reciprocal number (1 divided by the number)
00:22 Raise to the power multiplied by (-1)
00:26 Let's insert this into our exercise
00:34 Calculate the multiplication
00:42 This is the solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Simplify both expressions using exponent rules.
  • Step 2: Compare the simplified results to determine the appropriate sign.

First, simplify (10×3)7 (10 \times 3)^7 :
According to the power of a product rule, (ab)n=an×bn (ab)^n = a^n \times b^n . So,

(10×3)7=107×37(10 \times 3)^7 = 10^7 \times 3^7.

Now, simplify 1(15×2)7 \frac{1}{(15 \times 2)^{-7}} :
Firstly, address the negative exponent: (ab)n=1an×bn (ab)^{-n} = \frac{1}{a^n \times b^n} , so we have:

(15×2)7=1157×27(15 \times 2)^{-7} = \frac{1}{15^7 \times 2^7}.
Then, taking the reciprocal because of the double negative (when taking the reciprocal of inverse due to n -n ),

1(15×2)7=157×27\frac{1}{(15 \times 2)^{-7}} = 15^7 \times 2^7.

Now, compare the expressions:
Since 10=2×510 = 2 \times 5 and 15=3×515 = 3 \times 5, consider breaking each base into prime factors:

107×37=(27×57)×3710^7 \times 3^7 = (2^7 \times 5^7) \times 3^7,
157×27=(37×57)×2715^7 \times 2^7 = (3^7 \times 5^7) \times 2^7.

Both 107×3710^7 \times 3^7 and 157×2715^7 \times 2^7 resolve to the same product since they are permutations of the same multiplication.

Thus, we conclude:

The two expressions are equal, so the compatible sign is = = .

Therefore, the solution to the problem is = = .

Answer

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