Posted by **-Untamed-** on Thursday, November 24, 2011 at 9:14pm.

Find the Zeros of the following functions

f(x) = x/3 +5

^ That one is layed out so differently I don't understand how to solve.

In each of the following, determine the zeros of the function and determine the y-intercept of the graph of the function.

f(x) = 5x^2 - 35x

f(x) = 3x(x^2-49)

- Math -
**Steve**, Friday, November 25, 2011 at 12:05am
It's not so different. It just has a fraction. You can always use y instead of f(x)

y = x/3 + 5

To solve, set y=0 and solve for x

0 = x/3 + 5

x/3 = -5

x = -3/5

___________________

The y-intercept is always easy. Just plug in x=0 and evaluate y

y = 5x^2 - 35x

y(0) = 0 so the y-intercept is (0,0)

5x^2 - 35x

= 5x(x-7)

so, y=0 when

5x(x-7) = 0

x=0 or x=7

The x-intercepts are (0,0) and (7,0)

Note that (0,0) is both an x-intercept and a y-intercept.

_______________________

y = 3x(x^2 - 49)

Think back to your factoring exercises, and recall the difference of two squares:

(a+b)(a-b) = a^2 - b^2

y = 3x(x+7)(x-7)

So, the y-intercept is (0,0)

x-intercepts are (0,0) (7,0) and (-7,0)

## Answer this Question

## Related Questions

- advanced functions/precalculus - 1. The function f(x) = (2x + 3)^7 is the ...
- Maths - I have a test tomorrow and I really don't get this, please help me. "Use...
- calculus - For the following function f(x)=2x^4-6x^2+2x-1. Find the maximum ...
- functions - a) find the zeros of t(x) =2x^2 + ix + 3. b) The zeros are not ...
- 7th grade, math - Can someone explain the steps to solve this problem? If a ...
- college algebra - 1. solve the following logarithmic equation log_8(x+8)+log_8(x...
- Decartes Rule of Signs - Could you explain to me decartes Rule of signs? Here ...
- Algebra 2 - One of the the zeros of the functions F(x)= x^4+2x^3-13x^2-38x-24 is...
- college allgebra - f(x)=x^6+4x^5+4x^4+3x^3-x^2-5x+4 Find the maximum number of ...
- alg 2 - find all zeros of the following function: f(x)=x^3-x^2+4x-4 I have (x^2+...

More Related Questions