solve for x in the equation x^2-2x-35=0

Tutors, sign in to answer this question.

Hi Angela,

x2-2x-35=0

x2-7x+5x-35=0

x(x-7)+5(x-7)=0

(x-7)(x+5)=0

x-7=0 or x+5=0

x=7 or x=-5

Check: x=7 ,LHS = 49-14-35

=0 =RHS

x=-5, LHS = 25+10-35

=0=RHS

Ans: x=7 or x=-5

Meena from Strongsville,OH

This is a trinomial, and anytime the instructions call for factoring, first look for a GCF, but there is none in this problem. To factor a trinomial, use the AC method. AC means A*C, which is -35x^{2}. You need to find two terms that multiply to get -35x^{2}, but at the same time they need to add or subtract to get B, which is -2x. Make a T chart, and start listing the factors of -35, that add or subtract to get -2.

Because they have to mulitply to get a negative, and add or subtract to get a negative, then they must be different signs with the negative being larger. 5 and -7 will be the two factors to use. Now you can rewrite the problem as (x+5) (x-7) =0

To find out what x is, set each of the factors equal to 0, x+5=0 and x-7=0

On the first one, subtract 5 from both sides, and you get.....

On the second one, add 7 to both sides, and you get........

Hi Angela

To solve this quadratic equation, we need to factor. We can brake the x^{2}-2x-35=0 into two factors:

x^{2}-2x-35=0

(x-7)(x+5)=0

Then we set each factor equal to zero and solve for x:

(x-7)=0 (x+5)=0

x=7 x=-5

So the answer is x=7 and x=-5

Already have an account? Log in

By signing up, I agree to Wyzant’s terms of use and privacy policy.

Or

To present the tutors that are the best fit for you, we’ll need your ZIP code.

Your Facebook email address is associated with a Wyzant tutor account. Please use a different email address to create a new student account.

Good news! It looks like you already have an account registered with the email address **you provided**.

It looks like this is your first time here. Welcome!

To present the tutors that are the best fit for you, we’ll need your ZIP code.

Please try again, our system had a problem processing your request.