-3x^2+12=0 BEST ANSWER. What did i miss

-3(x^2-4)=0
-3(x+4)(x-1)=0
x+4=0 , x-1= 0
x=-4
x=1
-4,1

So why is this wrong? I think I followed every step. Can someone tell me what i missed?

Hi! Okay, so, when you took the x-squared minus 4 part and "unFOILed (factoring)" it, you put (x+4)(x-1). This is wrong because, when you FOIL it back again, it will be (x^2+3x-4), which was not a part of the original equation.
It should be (x+2)(x-2). (Try FOILing that back again. It's (x^2-4).)
Be sure to "reFOIL" your factor to check that you correctly factored it. :)

You're welcome!

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-3x^2 + 12 = 0; subtract 12 from both sides
-3x^2 + 12 - 12 = 0 - 12; simplify
-3x^2 = -12; divide both terms by -3
-3x^2/-3 = -12/-3; simplify
x^2 = 4; take the square root of both sides
√(x^2) = √(4); simplify & solve
x = +-2 <----------Answer

Blessings

Is this a quadratic equation??

I did:-
-3x² = -12 (i brought the +12 to the other side of 0 and changed the sign to +)

-12 divided by -3 = 4.

Square root of √4 = 2.

X=2, or -2

If you put 2 or -2 in the equation then you see it works.

-3x^2+12=0.
-3(x^2-4)=0
-3(x-2) (x+2)=0
Either x+2=0 or x-2=0
x1=-2
x2=2.

Proof: -2^2=-2*-2=4
4*-3=-12
-12+12=0

2^2=2*2=4
4*-3+-12
-12+12=0


You didn't factor correctly.

x^2 - 4 =/= (x+4)(x-1)
(x+4)(x-1) = x^2 + 3x - 4
One way solution to this problem is:
-3x^2 = -12
x^2 = 4
x = -2, 2

You didn't FOIL correctly.

(x+4)(x-1) doesn't equal (x^2-4). You need to do that part over again. Other than that, it looks good.

This : -3(x+4)(x-1)=0 does not un-foil to -3(x^2-4)=0

It unfoils to 3 (x^2 +3x -4)

You should have writen: -3 (x +2)(x-2)

Because x^2 - 4 factors into (x + 2)(x - 2), not (x + 4)(x - 1), which would be x^2 + 3x - 4

To the person ( 's) who called it FOIL: FOIL is an acronym for multiplying two binomials. What she was trying to do was to factor.

Agree with hivinng above.

-3x^2+12=0
-3x^2=-12
x^2=4
x=+/- 2

x = 2 or x = -2

x^2 - 4 = (x+2)(x-2)