X²+x-56=0 quadratic equations

Step-by-step explanation:

To solve the equation, factor x

2

+x−56 using formula x

2

+(a+b)x+ab=(x+a)(x+b). To find a and b, set up a system to be solved.

a+b=1

ab=−56

Since ab is negative, a and b have the opposite signs. Since a+b is positive, the positive number has greater absolute value than the negative. List all such integer pairs that give product −56.

−1,56

−2,28

−4,14

−7,8

Calculate the sum for each pair

−1+56=55

−2+28=26

−4+14=10

−7+8=1

The solution is the pair that gives sum 1.

a=−7

b=8

Rewrite factored expression (x+a)(x+b) using the obtained values.

(x−7)(x+8)

To find equation solutions, solve x−7=0 and x+8=0.

x=7

x=−8

step-by-step explanation:

no, her answer is not correct.   we square the lengths of all sides and then determine whether the pythagorean theorem holds here:

9² + 15² = 306.   this is not equal to the square of the longest side ( that square being 395.   answer c is correct.