Completing the square question (1 Viewer)

[BlueGas]

I need help with this question

 

[laters]

Look at the x^2 - 6x. The perfect square that produces an x^2 and a -6x is (x-3)^2
So (x-3)^2=x^2-6x+9 =====> x^2-6x+4=(x-3)^2-5

so a=3 and b=-5

 

[si2136]

If you can observe this equation, it is in the form of (x-a)^2 + b. Now if you expand it, it would be a quadratic equation!

Lets try to make it to this form. Since we can't factorise the quadratic equation, we can complete the square by moving 4 to the other side!

x^2 - 6x +/- ___= -4

What could be filled in ___ to complete the equation?

9 would work. So to add in a number, you would need to add it to the other side!

Therefore, x^2 - 6x + 9 = 5

Lets complete the square.

(x-3)^2 - 5

Therefore, a = 3, b = -5