# Pre Calc

posted by .

I am familiar with this type of problem but can't seem to get the right answer.

Use the given zero to find the remaining zeros of each function

f(x)=x^4-9x^3+7x^2-91x-348,zero 5-2i

I normally would use synthetic division with the root 5-2i bringing it down to x^3. Then synthetic with 5+2i, bring it down to a quadratic solve the quadratic then I'll have zeros, but I can't get past the 5-2i with the synthetic division. Every time I do it I can't get it to equal zero. I have done it multiple times and it won't work.

• Pre Calc -

One property of complex roots is that they always come in conjugate pairs.
So if one root is 5-2i, there will be another 5+2i
so there are two factors,
(x - 5 - 2i) and (x - 5 + 2i)

I multiplied these and go
(x^2 - 10x + 29)

Now do a long division of
(x^4-9x^3+7x^2-91x-348) by (x^2 - 10x + 29)
That should leave you with a quadratic, that can be solved for 2 more roots.
Let me know if it worked for you.

## Similar Questions

1. ### Pre Calc (For Reiny)

Thanks so much your method worked perfectly! My solution was: the remaining zeros were 5+2i, 3, and -4 I have one question that's bugging me though, why is it that synthetic division did not work for me?
2. ### college algebra

use the given zero to find the remaining zeros of each function.g(x)=x^3+3x^2+25x+75;zero:-5i
3. ### college algebra

use the given zero to find the remaining zeros of the function h(x)=x^4-15x^3+60x^2+70x-816 zero: 5-3i
4. ### Pre-calc

Use the given zero to find the remaining zeros of the function: h(x)=x^4-15x^3+55x^2+155x-1476 Zero:5-4i I multiplied [x-(5-4i)][x-(5+4i)] and got x^2-10x+9. The example I have says to divide that by h and get a second quadratic equation …
5. ### pre-cal

use the given zero to find the remaining zeros of the function. h(x)=x^4-12x^3+36x^2+68x-525 zero:4-3i
6. ### calculus

use the given zeros to find the remaining zeros of the function h(x)=x^4-9x^3+12x^2+138x-1360 zero:3-5i enter the remaining zeros of f please show work
7. ### math

use the given zero to find the remaining zeros of the function: F9x)=x^3-5x^2+4x-20; zero:2i I don't get it. Can someone please show me what to do with this?
8. ### use the given zero

Use the given zero to find the remaining zeros of the function. f(x)=x^3-2x^2+9x-18;zero;3i Enter the remaining zeros of f =
9. ### Algebra

Use the given zero to find the remaining zeros of the function. f(x)=x^3-2x^2+9x-18;zero;3i Enter the remaining zeros of f =
10. ### algebra

Use the given zero to find the remaining zeros of the function. (hx)= 3x^4+5x^3+25x^2+45x-18; zero:-3i labe

More Similar Questions