Solve each equation by using the quadratic formula

Question

2x^2+11x-51=0

Answer 1

Krisli,

 

The general quadratic polynomial equation is ax² + bx + c = 0, so a=2, b=11, and c=-51.

 

And the general solution is x = [-b  ±√(b² - 4ac)]/2a, substituting in your values

b2 - 4ac = (121) - 4(2)(-51) = 121 + 408 = 529, and the square root of 529 is 23.

 

So x₁   = [-11 + 23]/4 = 12/4 = +3 is one solution

and x₂ = [-11 - 23]/4  = -34/4 = - 17/2 is the other solution.