Answer:
x=-4
or
x=-5
Step-by-step explanation:
STEP
1
:
Equation at the end of step 1
((0 - 2x2) - 18x) - 40 = 0
STEP
2
:
STEP
3
:
Pulling out like terms
3.1 Pull out like factors :
-2x2 - 18x - 40 = -2 • (x2 + 9x + 20)
Trying to factor by splitting the middle term
3.2 Factoring x2 + 9x + 20
The first term is, x2 its coefficient is 1 .
The middle term is, +9x its coefficient is 9 .
The last term, "the constant", is +20
Step-1 : Multiply the coefficient of the first term by the constant 1 • 20 = 20
Step-2 : Find two factors of 20 whose sum equals the coefficient of the middle term, which is 9 .
-20 + -1 = -21
-10 + -2 = -12
-5 + -4 = -9
-4 + -5 = -9
-2 + -10 = -12
-1 + -20 = -21
1 + 20 = 21
2 + 10 = 12
4 + 5 = 9 That's it
