## Brooke2013 3 years ago Determine which binomial is a factor of -2x^3 + 14x^2 - 24x + 20 A.) x + 5 B.) x + 20 C.) x - 24 D.) x - 5

1. irkiz

its mcq so its easy to solve X is definitely wrong coz X is not the same as x

2. irkiz

if (x+5) is a factor, then x = -5 would make the equation 0

3. irkiz

if (x-5) is a factor, then x= 5 makes the equation 0

4. irkiz

substitute x = 5 and x = -5 see which one makes it 0

5. Brooke2013

Neither of them do.

6. irkiz

check again

7. Brooke2013

There all 4 little x's I just didn't mean to make the two middle one's capital x's.

8. Brooke2013

So I'll try the other two to see which one is right

9. irkiz

i managed to find the answer by substituting a value

10. irkiz

try x = 5 again

11. Brooke2013

ok, I will

12. Brooke2013

When I put the equation like this -2(5)^3 + 14(5)^2 - 24(5) + 20 I get 100 + 1900 - 120 + 20 and when you add it up it equals 4900

13. Brooke2013

Is the answer x = 5 ?

14. hartnn

yes, x=5 is the root , so x-5 is the factor.

15. Brooke2013

So the answer is D ? x - 5

16. hartnn

yup.

17. Brooke2013

I wish I understood how you got that bc I tried to plugg 5 into where the x's are and I got the answer 4900 not 0

18. hartnn

5^3 = 125 125*2 = 250

19. hartnn

5^2 = 25 25*14=350

20. hartnn

24*5=120

21. Brooke2013

Ok, thanks :)

22. hartnn

got it ?