Hence solve the equation - OCR Maths

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    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.
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    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
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    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.
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    Thank you but why do you use x^2?
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    (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
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    (Original post by pbms0101)
    Thank you but why do you use x^2?
    You have x^4-7x^2+12=0

    We can make it look like a quadratic by saying: (x^2)^2-7(x^2)+12=0

    Now let y=x^2 and you get y^2-7y+12=0
 
 
 
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