Question #72ff9

1 Answer
Nov 6, 2017

Read below

Explanation:

Let a=x+5 and b=x-5

Then, the equation reads a^2-b^2.

a^2-b^2=(a+b)*(a-b)

=((x+5)+(x-5))*((x+5)-(x-5))

=(2x)(10)

=20x

=4*(5x)

Since we know 5x is an integer (contained in ZZ), then the original expression is divisible by 4.