How do I solve this quadratic equation?

Question

x^2 + 8x + 15 = 0

A){-infiniti, -5} U {-3, infiniti}
B) {-5, -3}
C) {3,5}
D, {-1, -3}

Answer 1

easiest way in this case is plugging in numbers and see what equals zero, but if it wasn't multiple choice, you would want to factor. you have the coefficient of A (Ax^2 + Bx +c) being 1, so you just have to find out what factors of C can be added to get 8. since 5+3=8 and 5*3=15, you have your numbers now remeber that this means (x+5)(x+3) is your new equation, since anything times zero equals zero, if either equation is zero, the equation is solved, so set each equation equal to zero individually AKA
x+5=0 and x+3=0 now just solve and you get x=-3, -5 so B)

Answer 2

Use the quadratic equation listed in Section 5 at this link.

http://mathworld.wolfram.com/QuadraticEquation.html

Pay attention to the fact that your equation must be in the form

ax^2 + bx + c = 0

which your equation is. Plug in the relavent numbers and do the math. In your equation, x^2 + 8x + 15 = 0,

a = 1
b = 8
c = 15

You should get two answers which correspond with the choices you are given.

Answer 3

factorizing (x + 3)(x + 5) so B is the solution x1= -3, x2 = -5.

Answer 4

the solution is b : -3, -5

Answer 5

-5 works, and -3 works just plug and chug if you get stuck...

Answer 6

you should solve like every other quadratic

Answer 7

B....i just learned this myself and i love them!!!!!! have fun with math!! lol =]

Answer 8

good ?