Question

Find all the real zeros of the polynomial. Use the quadratic formula if necessary.

P(x)=x^3+6x^2+3x-20

Answer 1

Please show work.

Answer 2

how could you used the quadratic formula if the highest exponent was 3.

Answer 3

do you have any scientific calculator?

Answer 4

I don't know. I have a graphing calculator

Answer 5

good.

Answer 6

in your calculator press the mode button.

Answer 7

ok

Answer 8

then find the word equation

Answer 9

hmm...I can't seem to find it

Answer 10

by the way what's the brand of your calculator?

Answer 11

TI-84 Silver Edition

Answer 12

so Texas Instruments

Answer 13

You can find the first root by trial and error (\(x=-4\) works), divide that in, and use the quadratic equation on the remaining quadratic (\(x^{2}+2x-5)\), which yields \(x=1.236 \: / \: -3.236\)

Answer 14

sorry dude.. but I'm not familiar with that kind of calc.

Answer 15

thats ok

Answer 16

why don't you just try to factor it.

Answer 17

every time I try to factor it by grouping I get 0,-6, and 6 and 2/3, and I'm not sure if that's right because 6 and 2/3 isn't as clear as 0 and -6

Answer 18

do you know synthetic division?

Answer 19

yeah

Answer 20

use synthetic division

Answer 21

what would the divisors be?

Answer 22

your remainder must be zero

Answer 23

use trial and error

Answer 24

ok

Answer 25

find first the factors of 20 and synthetic division it to your f(x)

Answer 26

ok I'll do that

Answer 27

be sure you really know synthetic division ^_^

Answer 28

ok

Answer 29

Oops, put the wrong square root in my calculator. The final roots are \(x=1.449 \: / \: -3.449\)