Question

Use the technique of completing the square to transform the quadratic equation into the form (x+c)^2=a.
10x^2+80x+220=0
Can someone please explain this?

Answer 1

It's pretty, but hard to teach
first, u need simplify of 10x^2+80x+220=0
divided by 10 to both sides, giving us
x^2+8x+22=0
now, to get a perpect square form, setting become
x^2 + 8x + 16 + 6 = 0 or
x^2 + 8x + 16 = -6
(x+4)^2 = -6
sorry, if my explain not make sense

Answer 2

No. Most of it makes sense. But I don't get how you find the number for c.

Answer 3

if given (x+4)^2 = -6
compare the general form above : (x+c)^2=a
it mean, c=4 and a=-6