1. x^2+8x=20

a. Add (b/2)^2 to both sides of the equation.
b. Factor the left sides of the equation.

c. Take the square root of both sides of the equation from step 2.
d. simplify the radical and solve for x. show work.

Question

1. x^2+8x=20

 a. Add (b/2)^2 to both sides of the equation. 
b. Factor the left sides of the equation.

 c. Take the square root of both sides of the equation from step 2. 
d. simplify the radical and solve for x. show work.

johnweldon1993 · Answer

So step a)

Remember you have an equation that looks like

$$ax^2 + bx = c$$

So take 'b' (in your case 8) and divide it by 2 and square the result

(8/2)² = 16...so we add that to both sides of the equation

$$x^2 + 8x + 16 = 20 + 16$$

Step b) can you factor the left hand side of the equation?

johnweldon1993 · Answer

Step b)

When we factor this....we see it is a perfect square ...so

$$(x + 4)^2 = 36$$

Step c) Take the square root of both sides...what do you get after doing this?

johnweldon1993 · Answer

$$\sqrt{(x + 4)^2} = \sqrt{36}$$

Simplifes to

$$x + 4 = \pm6$$

So now you have 2 equations

$$x + 4 = 6$$
and
$$x + 4 = -6$$

Solve both equations for 'x' and you will have your answers

anonymous · Answer

thanks :D

anonymous · Answer

you helped me alot

johnweldon1993 · Answer

No problem! Just hope it made sense?

anonymous · Answer

it did! you should help me on other ones

johnweldon1993 · Answer

lol well if I see em posted and no one else helps then I'll be happy to lol

anonymous · Answer

lol ok