Factor the polynomial x2 + x - 6. Which one of the following is a factor?

I do a couple of them so you can get an idea how to do the rest:

15) x2 - 18x + 80.

x^2 - 18x + 80

(x - 8) (x - 10)

17) Solve the given equation by using the quadratic formula.

x2 - 7x - 4 = 0

ax² + bx + c = 0

x = [ - b ± √ (b² - 4ac) ] / 2a

in this case: a = 1, b = - 7, c = - 4

plug in and solve for x.

x = [ 7 ± √ (49 + 16) ] / 2

x = (7 ± √65) / 2

x = (7 ± 8.06) / 2

x = - 0.53, 7.53

The value under square root is 65.

20) Find the vertex of the parabola y = x2 - 4x

vertex >> x = - b/2a = 4/2 = 2

y = 2^2 - 4 (2) = 4 - 8 = - 4

vertex is at: (2, - 4)