SOLUTION: Find the set of values of x for which: x(x - 5) > 3(1 - x) It's just that it's many years since i've done these equations and was looking for some help with the example abov

Algebra ->  Absolute-value -> SOLUTION: Find the set of values of x for which: x(x - 5) > 3(1 - x) It's just that it's many years since i've done these equations and was looking for some help with the example abov      Log On


   



Question 7702: Find the set of values of x for which: x(x - 5) > 3(1 - x)


It's just that it's many years since i've done these equations and was looking for some help with the example above.
Many Thanks
Ivan

Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
x(x - 5) > 3(1 - x)
x%5E2+-+5x+%3E+3+-+3x
x%5E2+-+2x+-3+%3E+0

So we have a u-shaped quadratic, which when plotted on a graph may/may not cross the x-axis: wherever it does cross, those points are the roots.

The question says (at least my version of it) "where is the quadratic equation greater than zero"... visualising the u-shape, this will be any value of x to the left of the left root and any value of x to the right of the right root.

So...we need to find the roots!

x%5E2+-+2x+-+3+=+0
(x - 3)(x + 1) = 0

so EITHER x-3=0 OR x+1=0
so either x=3 or x=-1.

So where is the curve > 0?

answer is: x<-1 and x>3

jon.