Question

find the value of $(7{)}^5$.

• A. $12098$
• B. $14609$
• C. $16807$
• D. $3408$

Answer 1

The correct option is C $16807$

Let $x=(7{)}^5=[(7{)}^2{]}^2.7$

$x=\left[\right(8-1{)}^2{]}^2-7$

here $(a-b{)}^2=a^2-2ab+b^2$

$x=[8^2-2(8\left)\right(1)+1^2{]}^2.7$

$=(64-16+1{)}^2.7$

$=(49{)}^2.7$

$x=(50-1{)}^2.7$

$x=\left[\right(50{)}^2-2(5=)\left(1\right)+\left(1{)}^2\right].7$

$x=(2500-100+1)\times 7$

$x=\left(2401\right)\left(7\right)$

$x=16807$

so, $(7{)}^5=16807$