Islamic Forum

# Completing The Square

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:D

Find a and b so that the expression x^2 + 8x can be written as (x + a)^2 + b

Ok, explain to me really carefully and slowly im really thick lol

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:D

Basically what you need to do is half the number on front of the x, and put it in a bracket like this:

(x+4)^2

now if u multiply it out, you get the following:

x^2 + 8x + 16

But what u need is x^2 +8x, so u need to take away 16... therefore... u get

(x+4)^2 - 16

I hope that helps...

:D

Edited by jk_89

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Assalamu alaikum

I am quite sad, I've forgotten my A Level Maths skills!

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:D

Basically what you need to do is half the number on front of the x, and put it in a bracket like this:

(x+4)^2

now if u multiply it out, you get the following:

x^2 + 8x + 16

But what u need is x^2 +8x, so u need to take away 16... therefore... u get

(x+4)^2 - 16

I hope that helps...

:D

a=4 and b = -16

?

:D

yes :D

:D

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Can you believe I got an A in Pure Maths? :D

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