SOLUTION: If the area of a rectangle is 91m^2, and the dimensions are (x+2)m and (2x+3)m what is the value of x. I need to use the quadratic equation to find the value of x.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: If the area of a rectangle is 91m^2, and the dimensions are (x+2)m and (2x+3)m what is the value of x. I need to use the quadratic equation to find the value of x.      Log On


   

Question 444153: If the area of a rectangle is 91m^2, and the dimensions are (x+2)m and (2x+3)m what is the value of x. I need to use the quadratic equation to find the value of x.
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
(x+2)m * (2x+3)m=91
x(2x+3)+2(2x+3)=91
2x^2+3x+4x+6=91
2x^2+7x-85=0
Find the roots of the equation by quadratic formula

a= 2 b= 7 c= -85

b^2-4ac=49+680
b^2-4ac=729
sqrt(729)=27
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=(-7+27)/4
x1=5
x2=(-7-27)/4
x2= -8.5