Question

If the difference between the lengths of the sides of two squares is $4cm$ and the sum of the lengths of the sides of same two squares is $5cm$ then, what's the difference between the areas of both the squares?

• A. $15c{m}^2$
• B. $20c{m}^2$
• C. $25c{m}^2$
• D. $16c{m}^2$

Answer 1

The correct option is B $20c{m}^2$

We know that,
$(a^2-b^2)=(a+b)(a-b)$

Now,
Consider $a$ = side length of first square and b = side length of second square.

Given that,
$(a+b)=5cm$ and $(a-b)=4cm$

Thus,
Difference between the areas
of both the squares
$=5\times 4$
$=20c{m}^2$