Question

I'm having trouble solving -10t^5+15t^4+9t^3
I got t^3(-10t^2+15t+9) is this correct? not sure how to factor this

Answer 1

pull out the negative as well

Answer 2

-t^3( 10t^2-15t-9)

now if the quadratic factors nicely there are a few methods to approach it

Answer 3

so it should be t^3(10t^2+15t+9) ??

Answer 4

what i do is assume itll factor and set it up as such

(t- /10)(t+ /10)

then i work out the details

10*9 = 90

we would need to find that factors of 90 that subtract to get 15

Answer 5

1,90..89
2,45..43
3,30..27
6,15..11
5,18..13
10,9.. 1

unless i missed some factors, this doesnt break apart nicely

Answer 6

... that and 15-6 = 9, not 11 :) still not 15 tho

Answer 7

i thought it was set up as (5t-3)(-2t+3) to start i didn't the factor the t's yet.Am i heading in the right direction?

Answer 8

that will only get your outside terms; not your inside term

Answer 9

15+6 = 21 , not 15

Answer 10

we could try the quadratic formula to see what the roots are

Answer 11

\[x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}\]

Answer 12

as I undertand -1 is the gcf?
15=3*5
9=3*3
-10=2*-5 or 5*-2

Answer 13

\[x=\frac{15\pm\sqrt{15^2-4(10)(-9)}}{2(10)}\]
\[x=\frac{15\pm\sqrt{225+360}}{20}\]
\[x=\frac{15\pm\sqrt{585}}{20}\]

which means its not going to factor into nice little integers for us

Answer 14

im not sure what a gcf has to do with it ..... but then i am not up to speed with all the methods that are available either

Answer 15

How do read your previos post?

Answer 16

its a combonation of 2 values; the +- is regarded as shorthand. when 2 values have the same structure except for the operation; its simpler to combine them with the +-

Answer 17

otherwise im not sure what you mean by "read"

Answer 18

without the fraction bar

Answer 19

15 plus or minus the square root of 585, all divided by 20

Answer 20

oh thank you for help, the -10 first is throwing off

Answer 21

throwing me off

Answer 22

which is why i factored it out with the t^3

Answer 23

the negative tha tis :)

Answer 24

after you factor it out with -t^3 then you multiply -t^3 by all coefficients inside the ( ) ?

Answer 25

if you wanted to put it all back together again , yes.

but normally we factor to find roots or zeros or something that is easier to determine in the factored form

Answer 26

okay thank you for your help :)

Answer 27

yw