Question

If 4 is a solution to x^2+bx-12=0, then b=?

Answer 1

Answer:

b = -1

Step-by-step explanation:

First plug in 4 for each x:

$x^2+bx-12=0\\(4)^2+b(4)-12=0$

Then simplify by multiplying out what you can with 4:

$(4)^2+b(4)-12=0\\16+4b-12=0$

After simplify further by combining like terms:

$16+4b-12=0\\4b +4=0$

Then isolate b on one side by subtracting 4 from each side:

$4b+4=0\\(-4)+4b+4=0+(-4)\\4b=-4$

Finally isolate b further by dividing each side by 4 to get b alone and find the answer:

$4b=-4\\\frac{4b}{4}=\frac{-4}{4} \\ b=-1$