# algerbraaa easy question :)

Printable View

• Jan 5th 2010, 09:36 AM
johnsmith666
algerbraaa easy question :)
express x^2 - 5x + 1/4 in the form (x-a)^2 - b
• Jan 5th 2010, 09:41 AM
Archie Meade
$(x-a)^2=x^2-2ax+a^2$

$2a=5$

$a=\frac{5}{2}$

$(x-a)^2-b=x^2-2ax+a^2-b$

$a^2-b=\frac{1}{4}$

$\frac{25}{4}-b=\frac{1}{4}$
• Jan 5th 2010, 09:44 AM
johnsmith666
sorry im confuseddd :s i needed the answer in the form (x-a)^2 - b.
• Jan 5th 2010, 09:51 AM
Archie Meade
$b=\frac{25}{4}-\frac{1}{4}=\frac{24}{4}$

Now you have both 'a' and 'b'.

Practice with that.
• Jan 5th 2010, 09:55 AM
Archie Meade
"a" and "b" are both constants,
they have no 'x'.

When you multiply out $(x-a)^2$ you get

$(x-a)(x-a)=x(x-a)-a(x-a)=x^2-ax-ax+a^2=x^2-2ax+a^2$

This means $-5=-2a$

So you've got the value of 'a' now.
Use this value of 'a' to find 'b'.