Posted by **kelly** on Wednesday, May 4, 2011 at 9:52pm.

(-2,2) (4,20)

Find the value of x when y is 9.

- algebra help -
**Reiny**, Wednesday, May 4, 2011 at 10:35pm
I will assume you want

(-2,2) , (x,9) , and (4,20) to lie on the same straight line?

if so,

method I : find the equation of the line using the two known points, then sub in y=9

Method II : just set up a ratio ...

(x+2)/(9-2) = (4+2)/(20-2)

(x+2)/7 = 1/3

3x + 6 = 7

x = 1/3

- algebra help -
**Anonymous**, Saturday, May 21, 2011 at 2:07pm
how do you graph the function for p(x)=2x^2=12,500 where x is the number of items sold x(underscore)>3

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