Question

Solve x^2 - 8x - 20 = 0.

x = 4, x = -5

x = -4, x = 5

x = 2, x = -10

x = -2, x = 10

Answer 1

Do you know how to factor this?

Answer 2

Factoring it will give you the zeros of the polynomial (which is what you get with your answer choices from above)

Answer 3

i dont know about factoring =/

Answer 4

Factoring should work well. Alternative approaches include the quadratic formula and graphing.

You have a quadratic equation: x^2 - 8x - 20 = 0.

Look at the constant term, -20. What are some of the possible pairs of factors of that? for example, -20 = (-4)(5). But that pair must add up to the coefficient of x in the quadratic equation. Does it? No. So you'll have to find another set of factors of -20 and determine whether the sum of those two factors adds up to equal the coefficient of x.

Try it, please.

Answer 5

+20 factors into the following pairs: (1)(20), (2)(10), (4)(5).
1+20 =21
2+10=12
4+5 = 9

Would you please do the same thing for -20?

-20 factors into (-1)(20), (and what other pairs?)