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Math Help - Need guidance with rearranging a formula with two brackets and a letter that appears.

  1. #1
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    Need guidance with rearranging a formula with two brackets and a letter that appears.

    Hi guys. Basically as the title says can someone guide me through the problem of...

    Make x the subject of

    5(x-3) = y(4-3x)

    Thanks any help and guidance would be greatly appreciated.
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  2. #2
    Senior Member Paze's Avatar
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    Re: Need guidance with rearranging a formula with two brackets and a letter that appe

    Hi MattA147.

    The question being begged is: 'How do you solve this problem explicitly for x'.

    Changing the subject of a formula basically means that if you have a formula in the form: y=x+3 then the 'subject' of the formula is 'y'. Changing the subject to 'x' would yield: x=y-3.

    So in your problem we have: 5(x-3)=y(4-3x) and we want to make 'x' the subject of the formula.

    Let's start by getting rid of those parentheses:

    5(x-3)=y(4-3x)\\ \Rightarrow\\5x-15=4y-3yx

    Now let's solve for 'x':

    5x-15=4y-3yx\\ \Rightarrow\\5x+3yx=15+4y\\ \Rightarrow\\x(5+3y)=15+4y\\ \Rightarrow\\x=\frac{4y+15}{3y+5}
    Last edited by Paze; February 16th 2013 at 02:42 AM.
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