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General Science => General Science => Topic started by: malylo on 10/11/2011 03:01:47

Title: Find x-intercept and y-intercept for the function: f(x)=9x^2+12x+4.
Post by: malylo on 10/11/2011 03:01:47

Look at the function: f(x)=9x^2+12x+4. Please find x-intercept and y-intercept.


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Title: Find x-intercept and y-intercept for the function: f(x)=9x^2+12x+4.
Post by: CliffordK on 10/11/2011 04:31:16

y=9x²+12x+4

The Y-intercept is easy to calculate.  Just set X=0.

y=9*0²+12*0+4 = 4

To  calculate the X-intercept, it is easiest to first factor the quadratic, in this case it is relatively easy, a perfect square.
 
y=(3x+2)(3x+2)

Now, set Y=0.

0=(3x+2)(3x+2)

So, either half (which is the same) must equal zero.

0=3x+2

3x=-2

x=-2/3