Question

The area of a rectangle is given by A = x2 + 4x – 5. Find the value of x if the total area of the rectangle is equal to 7 square units.

Answer 1

\[7=x ^{2}+4x-5\]\[x ^{2}+4x-12=0\]
(x+6)(x-2)=0
x=-6
x=2

Answer 2

verify by susbstitution
\[A=2^{2}+4(2)-5=12-5=7\]
Since it is asking for x we can also\[A=(-6)^{2}+4(-6)-5=36-24-5=7\]

Answer 3

This is not a dimension (the -6), so don't let it distract you.