From the diagram we have
Base =

Height =

Area = Base × Height
126 =

⇒ Expand the double bracket
126 =

⇒ Subtract 126 both sides
0 =

⇒ Factorise the quadratic expression
0 =

⇒ Equating each factor to zero


We need the positive value of

so we use

Height = 5+1 = 6
Base = 4(5)+1 = 21
First let's review how to expand this!
(ax+b)^2=a^2*x^2+2abx+a^2
In this case
(2x^2+1/2)^2=2^2*x^2+2*1/2*2x+(1/2)^2
=4x^2+2x+1/4
Done!
The additive inverse of a number is important because it helps you to understand how to cancel terms for variables in equations and formulas.