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# Factorisation to solve equations

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1. Hi Guys

I'm brushing up for a maths entrance paper to to study A-level maths and a factorisation question has me stumped. I need to factorise a formula to solve the equation (= 0) and I can't work out how to do it. The formula is:-

9^x - 10 x 3^x + 9 = 0

I can work this out by trial and error, but the question said I should use factorisation to solve the equation, which I cannot do. Tips or advice appreciated.

Thanks.
2. (Original post by ChrisKH)
Hi Guys

I'm brushing up for a maths entrance paper to to study A-level maths and a factorisation question has me stumped. I need to factorise a formula to solve the equation (= 0) and I can't work out how to do it. The formula is:-

9^x - 10 x 3^x + 9 = 0

I can work this out by trial and error, but the question said I should use factorisation to solve the equation, which I cannot do. Tips or advice appreciated.

Thanks.
If you cant factorise then use the quadratic formula to work out roots which you must always do when the question asks to solve equation.
3. (Original post by ChrisKH)
Hi Guys

I'm brushing up for a maths entrance paper to to study A-level maths and a factorisation question has me stumped. I need to factorise a formula to solve the equation (= 0) and I can't work out how to do it. The formula is:-

9^x - 10 x 3^x + 9 = 0

I can work this out by trial and error, but the question said I should use factorisation to solve the equation, which I cannot do. Tips or advice appreciated.

Thanks.
Try a suitable substitution to turn it into something more familiar. (I'll give you a clue - it's to do with the powers of x, and the relationship between 3^x and 9^x.)

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