How do you solve 12x^2 + 2x = 012x2+2x=0?

1 Answer
Aug 1, 2015

x_1 = 0x1=0, x_2 = -1/6x2=16

Explanation:

You can solve this quadratic by factoring it to the form

2x(6x + 1) = 02x(6x+1)=0

The product of two distinct terms is equal to zero if either one of those terms is equal to zero, so you have

2x = 02x=0 or (6x+1) = 0(6x+1)=0

The solutions to these equations are

2x = 0 => x = color(green)(0)2x=0x=0

and

6x+1 = 0 => x = color(green)(-1/6)6x+1=0x=16

Alternatively, you could use the general quadratic form

color(blue)(ax^2 + bx + c = 0)ax2+bx+c=0

and recognize that c=0c=0, which implies that the quadratic formula

color(blue)(x_(1,2) = (-b +- sqrt(b^2 - 4ac))/(2a)x1,2=b±b24ac2a

is reduced to

x_(1,2) = (-b +- sqrt(b^2 + 4 * a * 0))/(2a) = (-b +- b)/(2a)x1,2=b±b2+4a02a=b±b2a

In your case, a=12a=12 and b=2b=2, so the two solutions will once again be

x_(1,2) = (-2 +- 2)/(24) = {(x_1 = (-2 +2)/24 = 0), (x_2 = (-2 -2)/24 = -1/6) :}