SOLUTION: The function below has at least one rational zero. Use this fact to find all zeros of the function. f(x)=7x^4 +27x^3 -40x^2 +x +5

Algebra.Com
Question 452448: The function below has at least one rational zero.
Use this fact to find all zeros of the function.
f(x)=7x^4 +27x^3 -40x^2 +x +5

Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
The function below has at least one rational zero.
Use this fact to find all zeros of the function.
f(x)=7x^4 +27x^3 -40x^2 +x +5
----
The sum of the coefficients is zero, so x = 1 is a zero.
---
Use synthetic division to find other zeroes:
---
1)....7....27....-40....1....5
.......7.....34.....-6...-5...|..0
------
The quotient, 7x^3+34x^2-6x+5 has a zero
at x = -5, which I found using
a graphing calculator.
-5).......7.....34.....-6...-5
...........7.....-1.....-1...|..0
---
Use the quadratic formula to find the zeroes
of 7x^2-x-1 = 0
===========================
Cheers,
Stan H.
===========

RELATED QUESTIONS

h(x)= 3x^4+17x^3+10x^2+x+5 The function below has at least one rational zero. Use... (answered by richard1234,MathTherapy)
The function below has at least one rational zero. Use this fact to find all zeros of... (answered by Edwin McCravy)
find a rational zero of the polynomial function and use it to find all the zeros of the... (answered by lwsshak3)
4.6 The following function is given. f(x)=x^3 -5x^2 -9x+45 a. List all rational... (answered by Boreal)
Find a rational zero of the polynomial function and use it to find all the zeros of the... (answered by stanbon)
Find a rational zero of the polynomial function and use it to find all the zeros of the... (answered by Fombitz)
Find a rational zero of the polynomial function and use it to find all the zeros of the... (answered by stanbon)
find a rational zero of the polynomial function and use it to find all the zeros of the... (answered by stanbon)
4.6 The following function is given. f(x)=x^3 -5x^2 -9x+45 a. List all rational... (answered by Boreal,ikleyn)