SOLUTION: Find the x-intercept for the parabola whose equation is given. If the x-intercepts are irrational, round your answers to the nearest tenth. y=-x2+19x-90

Algebra ->  Equations -> SOLUTION: Find the x-intercept for the parabola whose equation is given. If the x-intercepts are irrational, round your answers to the nearest tenth. y=-x2+19x-90      Log On


   

Question 1067603: Find the x-intercept for the parabola whose equation is given. If the x-intercepts are irrational, round your answers to the nearest tenth. y=-x2+19x-90
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
y=-x%5E2%2B19x-90 intersects the x-axis (the y=0 line) when y=0 ,
so you have to solve the equation
-x%5E2%2B19x-90=0 .
Since I do not like that minus sign at the left end,
I would multiply both sides of the equal sign times -1 to get
the equivalent equation x%5E2-19x%2B90=0 .
Then I would factor that polynomial as
%28x-10%29%28x-9%29=0 ,
and that would tell me that the solutions of the equation are
the solution of x-10=0 and
the solution of x-9=0 .
Those solutions are
highlight%28x=9%29 and highlight%28x=10%29 .