check my answer please

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haliebre

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Apr 4, 2006
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for x2-4/3x +4/9 I changed to 9x2 -12+4 and then I factored it and got x+ 1/3 and x=4/3. Did I do this right?
 
Um, what were the complete instructions? How can you have x+ 1/3 and x=4/3 as a solution, anyway?
 
HOW did you get that?

9x^2 - 12x + 4 = 0
(3x - 2)(3x - 2) = 0 : capish?
 
haliebre said:
So x = 2/3?
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We don't know: you haven't told us what the instructions were. Are you solving, and forgot to tell us what was on the other side of the "equals" sign? Are you find the zeroes? The vertex? Putting this in completed-square form?

Please reply with the full text of the exercise. Thank you.

Eliz.
 
haliebre said:
The instructions were to solve by any method.
Click to expand...
Okay then: what was the posted expression equal to?

Also, you posted "x2-4/3x +4/9". This could mean the following:

. . . . .x2 − 43x + 49\displaystyle \large{x^2\,-\,\frac{4}{3x}\,+\,\frac{4}{9}}

Is that what you meant? Or did you mean something like one of the following?

. . . . .x2 − 43x + 49\displaystyle \large{\frac{x^2\,-\,4}{3x}\,+\,\frac{4}{9}}

. . . . .x2 − 43x + 49\displaystyle \large{x^2\,-\,\frac{4}{3}x\,+\,\frac{4}{9}}

When you reply with what the expression was equal to, please include all the steps you did in the solving process. Thank you.

Eliz.
 
haliebre said:
It was equal to 0 and the first way you wrote it was correct.
Click to expand...
So the original exercise was as follows:

. . . . .Solve the following:

. . . . .x2 − 43x + 49 = 0\displaystyle \large{x^2\,-\,\frac{4}{3x}\,+\,\frac{4}{9}\, =\,0}

That still leaves us wondering how you obtained solutions of x = 4/3 and x = 1/3, since:

. . . . .x<sup>2</sup> - 4/(3x) + 4/9 = 0

. . . . .[4/3]<sup>2</sup> - 4/(3[4/3]) + 4/9 ?=? 0

. . . . .16/9 - 1 + 4/9 ?=? 0

. . . . .20/9 - 1 ?=? 0

. . . . .20/9 - 9/9 = 11/9 ?=? 0

So "x = 4/3" doesn't work. And:

. . . . .x<sup>2</sup> - 4/(3x) + 4/9 = 0

. . . . .[1/3]<sup>2</sup> - 4/(3{1/3]) + 4/9 ?=? 0

. . . . .1/9 - 4 + 4/9 ?=? 0

. . . . .5/9 - 4 ?=? 0

. . . . .5/9 - 36/9 = -31/9 ?=? 0

So "x = 1/3" doesn't work.

Please reply showing your steps. For instance, first you multiplied through to clear the denominators. What did you multiply by? What did you get? What did you do next?

Thank you.

Eliz.
 
The answer I got was x=2/3. I cleared it of fractions first by multiplying through by 9. then I factored it to look like (3x-2)(3x-2)=0 and derived at the answer x=2/3
 
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