Question

The length of rectangle is ( a- b) cm and breath is ( a+b) cm , b=(28-2a) where a square of 5 , find the area of rectangle

Answer 1

Area of rectangle =lb
=(a+b)(a-b)
=a^2-b^2
=a^2-(28-2a)^2
=a^2-(784+4a^2-112a)
=a^2-784-4a^2+112a
=-3a^2-784+112a