# [SOLVED] Having trouble with finding rational zeros for each function??

• Feb 11th 2009, 11:51 AM
twiggy5492
[SOLVED] Having trouble with finding rational zeros for each function??
state all possible rational zeros for the function

here is one of the problems i'm having trouble with:

f(x)= x^3+2x-3x+5

i know: p= +1, -1, +5, -5
q= same

but none of them seem to equal to zero when i put them in (Headbang)<---me

one that i have NO IDEA how to do is:

find all rational zeros for each function

f(x)= (x-3)(x+5)(2x+5)

Thanks for any help in advance -Liza
• Feb 11th 2009, 12:35 PM
masters
Quote:

Originally Posted by twiggy5492
state all possible rational zeros for the function

here is one of the problems i'm having trouble with:

f(x)= x^3+2x-3x+5

i know: p= +1, -1, +5, -5
q= same

but none of them seem to equal to zero when i put them in (Headbang)<---me

Hi Liza,

So, I guess it doesn't have any rational zeros, huh? And are you sure you didn't make a typo there. Should it be:

\$\displaystyle f(x)=x^3+2x^2-3x+5\$

Either way, there are no rational zeros.

Quote:

Originally Posted by twiggy5492
one that i have NO IDEA how to do is:

find all rational zeros for each function

f(x)= (x-3)(x+5)(2x+5)

Thanks for any help in advance -Liza

\$\displaystyle f(x)= (x-3)(x+5)(2x+5)\$

\$\displaystyle (x-3)(x+5)(2x+5)=0\$

\$\displaystyle x-3=0\$

\$\displaystyle x+5=0\$

\$\displaystyle 2x+5=0\$

Solve the above 3 equations to find your zeros.