15. x^2 +4x - 12 = 0
We need to find square roots of this equation.
solutions are x1 = 2 and x2 = -6
using factoring we can write this equation in a form:
a* (x-x1) * (x-x2) where "a" is coefficient in front of x^2 ( in this case its 1)
therefore solution is
(x-2) and (x+6)
17. d) is the answer. To solve these kinds of questions just multiply factors and see if they match your expression.
18. again, we solve equation 24x^2 -4x -8 = 0
x1 = -1/2 and x2 = 2/3
24(x+1/2)*(x-2/3)
8(x+1/2)*(3x-2)
(8x + 4)*(3x-2)
answer is b)
