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# Hence solve the equation - OCR Maths Watch

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1. Solve the equation y²-7y+12=0

Hence solve the equation x4-7x²+12=0

I understand how to factorise the first part but how do i use that to help with the second equation.
2. so the first part factorised is (y-3)(y-4)
the second equation is pretty much the same it just has different powers of x
so you take the first answer switch the y's for x's and make it x squared because x^2 times x^2 is x^4
3. The second equation has just used the substitution of y = x^2, so in your answer to part a), do the same and replace y with x^2 and solve this.
4. Thank you but why do you use x^2?
5. (Original post by pbms0101)
Thank you but why do you use x^2?
Well, what happens when you put y = x^2 into the new equation you have been asked to solve?

Also, if you quote someone like I have done so now, they will know you have responded
6. (Original post by pbms0101)
Thank you but why do you use x^2?
You have

We can make it look like a quadratic by saying:

Now let and you get

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