x^2 + 9x = -20
Rearrange:
x^2 + 9x - (-20) = 0
x^2 + 9x + 20 = 0
the Equation has the form:
ax^2 + bx +c = 0
Where:
a=1
b= 9
c= 20
Find the sum of 2 numbers that equal b, and multiplied equal c.
4+5= 9 (b)
4x5 =20 (c)
Factor:
(x+ 4) (x+5) = 0
Equal each equation to zero and solve for x
x+4= 0
x= -4
x+5=0
x=-5
Solution:
x=-4 , x =-5