A Math Question

Question

1. The length of a tablet screen is 7cm longer than its width if the total area is 540cm^2.Calculate the length of the tablet.

Answer 1

L= 7+W

LW = 540

W= 540/L

L= 7+540/L multiply by L

L^2 = 7L +540

L^2 -7L -540 = 0 use the quadratic formula

L = 7/2 + (1/2)sqr(49+4(540)) = 3.5 + 23.5 = 27 cm long

or you could have factored the quadratic

(L-27)(L+20) = 0

L=-20 and 27 ignore the negative solution

W= 27-7 = 20 cm

LW =27 x 20 = Area = 540 cm^2