Question

Medal and Fan. Solve x^2-4x-21=0 by factoring and the zero product property. (ab=0 if a=0 OR b=0)

Answer 1

find two numbers that multiply to -21 and add to -4 at the same time

Answer 2

-7 and 3.

Answer 3

so x^2 - 4x - 21 = 0 turns into (x-7)(x+3) = 0

Answer 4

Okay. But.. what about the -4x..? I get confused when it comes to factoring.

Answer 5

I got the -4 from the -4x

Answer 6

so that's why x^2 - 4x - 21 factors to (x-7)(x+3)

-7+3 = -4
-7*3 = -21

Answer 7

Ohh!! duh. Okay. Continue please (:

Answer 8

so you have (x-7)(x+3) = 0

Answer 9

use the zero product property to break up (x-7)(x+3) = 0 into

x-7 = 0 or x+3 = 0

x = ??? or x = ???

Answer 10

So then x=7 or x=-3.. yeah?

Answer 11

both are correct

Answer 12

Ahh! thank you, so much easier than I was making it.

Answer 13

you're welcome

Answer 14

Do you have time for one more?

Answer 15

sure

Answer 16

Okay. I need to know how to find the relative maximum and minimum of a function. I'm given f(x)=2x^3+x^2-11x

Answer 17

Since you're not in calculus, you'll need to use a graphing calculator to get the answer

Answer 18

https://www.desmos.com/calculator is a good graphing calculator

Answer 19

Luckily I'm familiar with that site (: Okay.. so now what?

Answer 20

relative maximum = highest point in a certain region
relative minimum = lowest point in a certain region

Answer 21

type in 2x^3+x^2-11x and look for the turning points

Answer 22

Okay.