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# C1 equation question watch

1. Hi, the equation is (4x) over (x-1) = (6) over (x-3)

I have cross multiplied, expanded then made the quadratic equal 0. Then I have tried to solve using the quadratic formula and have the answer:

(+18 +/- root 228) over 8 but the answer in the book is (+9 +/- root 57) over 4

but by simplifying my answer wouldn't I get (+9+/- root 114) over 4 instead of root 57?

So I am stuck

I am grateful for any help

Thanks
Millie
2. (Original post by Peace&Love)
Hi, the equation is (4x) over (x-1) = (6) over (x-3)

I have cross multiplied, expanded then made the quadratic equal 0. Then I have tried to solve using the quadratic formula and have the answer:

(+18 +/- root 228) over 8 but the answer in the book is (+9 +/- root 57) over 4

but by simplifying my answer wouldn't I get (+9+/- root 114) over 4 instead of root 57?

So I am stuck

I am grateful for any help

Thanks
Millie
If you take a factor 2 inside a square root it becomes a factor of 4

3. (Original post by Peace&Love)
Hi, the equation is (4x) over (x-1) = (6) over (x-3)

I have cross multiplied, expanded then made the quadratic equal 0. Then I have tried to solve using the quadratic formula and have the answer:

(+18 +/- root 228) over 8 but the answer in the book is (+9 +/- root 57) over 4

but by simplifying my answer wouldn't I get (+9+/- root 114) over 4 instead of root 57?

So I am stuck

I am grateful for any help

Thanks
Millie

Then using this you can take out a factor of 2 from the numerator and the denominator and cancel to leave you with that desired answer.
4. (Original post by Robbie242)

Then using this you can take out a factor of 2 from the numerator and the denominator and cancel to leave you with that desired answer.

Thanks so much I now understand
5. it is easier to divide out a common factor in the quadratic equation before you use the formula.

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Updated: October 13, 2013
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