Now x^2 - 2x - 15 is a parabola pointing up with roots x = -3 and x = 5. Therefore, it will be > 0 to the left of smaller root (x < -3), and to the right of larger root (x > 5)
x^2 - 2x ≥ 15
x^2-2x-15≥ 0
(x+3)(x-5)≥ 0
At x-axis, when f(x)=0,
(x+3)(x-5) =0
x=-3 or x=5
If you do a sketch of the graph of this quadratic function, it is concave up and you will also notice that only any x-values less than 3 or greater than 5(i.e.,x<-3 or x>5) will result in the inequality greater than 0.
ok, you have even have been given your self a share. you could resolve any share with the help of "flow multiplying." it will make greater experience in case you in case you positioned 10/a million=20/x. You multiply the right with the different backside. (the 1st numerator with the 2d denominator) 20=10x is what you get. then you definitely divide the two facets with the help of 10 to get: x=2