SOLUTION: Please help me to solve this problem: {{{ x2-4x-7 = 0 }}}, Determine whether the following equation have a solution or not? Justify your answer.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: Please help me to solve this problem: {{{ x2-4x-7 = 0 }}}, Determine whether the following equation have a solution or not? Justify your answer.      Log On


   

Question 180884: Please help me to solve this problem: +x2-4x-7++=+0+, Determine whether the following equation have a solution or not? Justify your answer.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

From x%5E2-4x-7 we can see that a=1, b=-4, and c=-7


D=b%5E2-4ac Start with the discriminant formula.


D=%28-4%29%5E2-4%281%29%28-7%29 Plug in a=1, b=-4, and c=-7


D=16-4%281%29%28-7%29 Square -4 to get 16


D=16--28 Multiply 4%281%29%28-7%29 to get %284%29%28-7%29=-28


D=16%2B28 Rewrite D=16--28 as D=16%2B28


D=44 Add 16 to 28 to get 44


Since the discriminant is greater than zero, this means that there are two real solutions.