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# Help with grouping symbols Watch

1. Just a quick question regarding this example in my book.

When it comes completing the square and taking out the coefficient of 2 in this example.

2x^2-10x
= 2(x^2-5x)
= 2[(x-5/2)^2 -(5/2)^2]
= 2[(x-5/2)^2 - 25/4]
= 2(x-5/2)^2 - 25/2

How come the answer is 2(x-5/2)^2 - 25/2 and not 2(x-5/2)^2 - 25/4 ?

Thanks for the help in advance!

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2. (Original post by dthomas86)
Just a quick question regarding this example in my book.

When it comes completing the square and taking out the coefficient of 2 in this example.

2x^2-10x
= 2(x^2-5x)
= 2[(x-5/2)^2 -(5/2)^2]
= 2[(x-5/2)^2 - 25/4]
= 2(x-5/2)^2 - 25/2

How come the answer is 2(x-5/2)^2 - 25/2 and not 2(x-5/2)^2 - 25/4 ?

Thanks for the help in advance!

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Becuase:
3. It is like that:

because of the fact that
4. Cheers guys. Just to double everything outside of the brackets gets multiplied by everything inside the parentheses?

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5. Is this correct? ^

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6. (Original post by dthomas86)
Cheers guys. Just to double everything outside of the brackets gets multiplied by everything inside the parentheses?

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(Original post by dthomas86)
Is this correct? ^

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I'm having trouble understanding what you're asking!

If you mean does a(b + c) = ab + ac, then yes

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