Question

The area of a square of sides
(x + 4) cm is 20 cm^{2} .What is the area of a rectangle of length
(x +8) cm and width x cm?

Answer 1

Step-by-step explanation:

${(x + 4)}^{2} = {20}^{2 }$

${x}^{2} + 16 + 8x = 400$

${x}^{2} + 8x - 384 = 0$

${x}^{2} + 24x - 16x - 384 = 0$

$x(x + 24) - 16(x + 24) = 0$

$(x + 24) = 0 \\ x = - 24 \\ not \: possible$

$(x - 16) = 0 \\ x = 16cm \\ possible$

so x=16

area of rectangle=(16+8)×16

=24×16

=384cm