Question

Simplify the following:

${(-3)}^4\times 7^4$

• A. ${(-21)}^4$
• B. ${(-21)}^{-4}$
• C. ${(-1)}^4$
• D. None of these

Answer 1

Answer: (A)

${(-21)}^4$

We know that,

$(-a{)}^4=a^4$ as $4$ is even

So, $(-3{)}^4=3^4$

We know that,

$a^m\times b^m=(ab{)}^m$

So, $3^4\times 7^4=(3\times 7{)}^4=(21{)}^4=(-21{)}^4$ Since product is positive if exponent is even.