Question

Solve x2 – 4x = 12 by completing the square

Answer 1

\[\large{x^2-4x-12=0}\] right?

Answer 2

you just add 4 to both sides.
that will make it
\[(x-2)^{2}=16\]

Answer 3

@mathslover yes

Answer 4

ok so now ..
\[\large{x^2-4x-12=x^2-4x+4-16=0}\] right?

Answer 5

Yeah

Answer 6

now can u write \[\large{x^2-4x+4=(x-2)^2}\] ??

Answer 7

(x)^2 -2(2)(x)+2^2 = a^2-2ab+b^2=(a-b)^2=(x-2)^2

Answer 8

Stuck

Answer 9

ok so : (x^2-4x+4) = (x-2)^2 ?

Answer 10

x^2-4x-12=0
x=-2
x=6? or am I doing it wrong

Answer 11

I think you are doing it wrong ; :
x^2-4x-12 = 0

\[\large{x^2-4x+4-16=0}\]
\[\large{(x-2)^2-16=0}\]
\[\large{(x-2-4)(x-2+4)=0}\]
\[\large{(x-6)(x+2)=0}\]

hence either x = 6 or x = -2

Answer 12

always remember that :
\[\large{(a-b)^2=a^2-2ab+b^2}\]
\[\large{(a+b)^2=a^2+2ab+b^2}\]

Answer 13

or : \[\large{(a\pm b)^2=a^2\pm 2ab +b^2}\]

Answer 14

You're awesome! Thank you so much! The formulas were very helpful :)

Answer 15

nice to hear .. :) best of luck