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There's a question in my textbook:

$5x-6-(3x-2)$

I think I misunderstood as I put the following for my working out:

$5x-6-3x-2$

And from that I got:

$2x-8$

Can anyone help me to understand how to get the right answer?

  • 3
    When you subtract (3x-2), you need to change the sign on both 3x and -2. So $5x - 6 - (3x - 2) = 5x - 6 - 3x + 2$.2011-09-22

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Think of subtracting the quantity in the parentheses as a application of the distributive power. Consider that: $5x-6-(3x-2) = 5x-6+(-1(3x-2))$ As adding a negative is the same as subtracting a positive. Then, just distribute the -1 over the quantity in parentheses so:$5x-6-(3x-2) = 5x-6+(-3x+2))$ As the -1*-2 becomes a +2 and the -1(3x) is merely -3x. Now, as there's nothing multiplying the quantity in parentheses, you can simply take them off and get:$5x-6-(3x-2) = 5x-6-3x+2$ Hopefully that clarifies things for you, but feel free to comment if something is unclear.