Question

I am having some problems solving a couple different equations. Please help. The first one says solve by completing the square: x^2+3x-70=0

Answer 1

the aim of completing the square is to obtain a perfect square on one side of equation and a number on other side

Answer 2

since you said to complete the square move the -70 over to the right side of the = sign
x^2+3x=70
now take half of the coefficient of x and square it... (3/2)^2. this is what you need to make the left side a perfect square trinomial. and don't forget to add the same amount to the right.
x^2+3x+(3/2)^2=70+(3/2)^2
now the left side is factored as
(x+3/2)^2=70+9/4
can you take it from here?

Answer 3

I have tried that on another problem that i had and the answers I came up with were wrong. So I have an error in one of my steps. Just not sure where it is.

Answer 4

I can sure try to take it from there.

Answer 5

btw... your answer should be -10, 7. solving the equation by factoring should be much easier...

Answer 6

Ok I am not getting close to that. I don't know where I am going wrong.

Answer 7

I'm confused that you mention about different equation,
anyway here is how to complete square:
x^2+3x-70=0
(x + 3/2)² - 70 - 9/4
(x + 3/2)² - 289/4

Answer 8

Different problems I am working on...this is just one of them I needed help with.

Answer 9

Ok thats what I did....so you subtract the 289/4?

Answer 10

That's called complete square! finished!

Answer 11

so how do I come up with the answer? -10 and 7, which was correct in mymathlab.

Answer 12

What you ask now is solve it by fraction!

Answer 13

Sorry fractions are something that I don't understand how to do especially when using in formulas.

Answer 14

When you apply product and sum method to factor:
(x + 10) ( x -7) = 0

Answer 15

x + 10 = 0 --> x = -10
x - 7 = 0 --> x = 7

Answer 16

ahha...got it...thanks for explaining further.

Answer 17

:)