Question

The dimensions of a rectangular garden were 3 m by 10 m. When both dimensions were increased by equal amounts, the area of the garden doubled. Find the dimensions of the new garden.

Answer 1

A=l*w

A=3*10

30=A

add x to l and w the area doubled

60 = (3+x)(10+x)

FOIL

60 = 30 +3x+10x+x^2

60 = x^2 +13x+30

subtract 60 from each side

0=x^2 +13x-30

factor

0=(x+15) (x-2)

x+15=0  x-2=0

x=-15  x=2

x cannot be negative so x=2

new dimensions

3+2, 10+2

Answer: 5m ,12m