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Mathematics: Post your doubts here!

Serenia

Serenia

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Hello. Can anyone please answer this question:
Express 4x^2-12x in the form (2x+a)^2+b.
This question is in the Pure Maths 1 paper 11 of the May/June 2014 session.
The answers on the mark scheme are a=-3 and b=-9.
I know how to complete the square when the coefficient of x is not 1, but, I can't do this one because x has a coefficient of 2 in the form in which they want the expression. I don't know how to go about it.
Thank you.
 
W

Wkhan860

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Serenia said:
Hello. Can anyone please answer this question:
Express 4x^2-12x in the form (2x+a)^2+b.
This question is in the Pure Maths 1 paper 11 of the May/June 2014 session.
The answers on the mark scheme are a=-3 and b=-9.
I know how to complete the square when the coefficient of x is not 1, but, I can't do this one because x has a coefficient of 2 in the form in which they want the expression. I don't know how to go about it.
Thank you.
Click to expand...
Well it isn't tht hard....just put the 2 eqtns as equalant to each other nd expand (2x+a)+b
Aftr expanding it compare the values on Both syds
 
robinhoodmustafa

robinhoodmustafa

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Serenia said:
Hello. Can anyone please answer this question:
Express 4x^2-12x in the form (2x+a)^2+b.
This question is in the Pure Maths 1 paper 11 of the May/June 2014 session.
The answers on the mark scheme are a=-3 and b=-9.
I know how to complete the square when the coefficient of x is not 1, but, I can't do this one because x has a coefficient of 2 in the form in which they want the expression. I don't know how to go about it.
Thank you.
Click to expand...

Please share the solution with me too :)
 
W

Wolfgangs

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Can someone please solve this question as soon as possible? (P31 M/J 2013)
 

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The Sarcastic Retard

The Sarcastic Retard

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Wolfgangs said:
Can someone please solve this question as soon as possible? (P31 M/J 2013)
Click to expand...
i) http://sketchtoy.com/64179135
ii) Non of my credits, "As line in parallel to x-axis so parallel vector of the line will be 1,0,0
equation of the line, r=(7,7,-5)+t(1,0,0)=(7+t,7,-5)
put these values of x,y,z in the equation of plain, and find the value of t.
find B by putting this value of t into equation of the line n find |AB|"
 
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