# math

posted by .

Solve 3x^2-8x+4=0 by graphing. If exact roots cannot be found, state the consecutive integers between which the roots are located.

A)2;between 0 and 1
B)between 0 and 1;between 7 and 8
C)1,2
D)between 0 and 1;between 3 and 4

I don't understand this one either its gotta be A or C I don't undertand what I got from a website which gave me X1=2 and X2=.6 repeating

• math -

let y = 3x^2-8x+4 or f(x) = 3x^2-8x+4 , same thing

try a few x's
I tried -1,0,1,2,3 and y values of
15,4,-1,0,7

notice when x = 0 the graph is above the x-axis, but when x=1 the graph is below the x-axis.
So there has to be a solution between x=0 and x=1
Also notice when x=2 , y =0, so x=2 is a solution.

Solutions to equations are where the matching graph cuts the x-axis.

Now that we know that we have an exact solution at x=2, x-2 must be an exact factror, and sure enough

3x^2-8x+4 = (x-2)(3x-2)

so x=2 or x=2/3

• math -

So C would be the choice?

• math -

NOOO, it is A

Did you not read when I said:

"notice when x = 0 the graph is above the x-axis, but when x=1 the graph is below the x-axis.
So there has to be a solution between x=0 and x=1
Also notice when x=2 , y =0, so x=2 is a solution. "

• math(typo) -

Oh yeah duh. my mistake