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September 20, 2014

September 20, 2014

Posted by **Jenny** on Monday, September 1, 2008 at 9:35pm.

2x^2-18x=0, x^2=6x+7, 6y^2+5y-6=0

Also

SOLVE FOR X CORRECT TO 4 DECIMAL PLACES:

x^2+6x+2=0 2x+4=3x^2

- Algebra -
**David Q**, Tuesday, September 2, 2008 at 3:03pmFor the first bit of the question, get all the terms over onto the left-hand side of the equation. For example, take the second one:

X²-6X-7=0

Usually you can factorize it easily into the following form: (X+A)(X+B). (There's no guarantee that it's an easy factorization, but if you're expected to solve it this way it usually is.)

If you multiply out those two brackets, you'll get X² + (A+B)X + AB.

So in this example, if you compare the corresponding terms from the two equations, A + B = -6 and AB = -7. So what are A and B? Usually you can spot it in a few seconds...

How about A = 1 and B = -7?

One down, two to go...

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