What are the zeros of f(x) = x2 + x - 20?
A. X = -5 and x = 4
B. X = - 4 and x = 5
C. x = -2 and x = 10
D. x = -10 and x = 2

A. x = -5, 4

Step-by-step explanation:

0 = x^2 + x -20

0 = (x + 5)(x - 4)

x = -5, 4

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.

x = 3 ± √(5+y)