# Help, stuck on a past paper question for GCSEWatch

This discussion is closed.
#1
For all values of x,

x^2+4x = (x+p)^2+q

find the values of p and q

if anyone solves can they plz show working, i got exam 2moro
0
14 years ago
#2
x^2+4x = (x+p)^2+q

x^2 + 4x = (x + 2)^2 - 4
0
#3
where did 2 and -4 come from
0
14 years ago
#4
where did 2 and -4 come from
say you have ax^2 + bx + c
In your example, a = 1, b = 4 and c = 0.

halve b, and put it in the brackets. then minus the square of what you just put in the brackets from c.

Eg.

x^2 + 6x + 3

Halve the 6, put in the brackets:
And take the square of the new number (9) from c:

(x + 3)^2 - 9 + 3
(x + 3)^2 - 6

Eg.

x^2 + 10x - 5
(x + 5)^2 - 25 - 5
(x + 5)^2 - 30
0
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