SOLUTION: a^2+2a < or equal to 15 Thanks, P

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Question 23331: a^2+2a < or equal to 15
Thanks,
P

Answer by philberg99(10) About Me  (Show Source):
You can put this solution on YOUR website!
To do this problem, think about the quadratic a%5E2%2B2a-15. Where is this quadratic zero? Note that the quadratic factors to (a-3)(a+5), so it is zero when a = 3 and when a = -5.
Now when is the quadratic bigger than zero? To solve this, think about graphing the quadratic.
+graph%28+300%2C+200%2C+-8%2C+4%2C+-10%2C+10%2C+x%5E2%2B2x-15%29+
The graph tells us that it is bigger than zero when x [or in our case, a] is less than -5 or greater than 3.
So the solution to this is x%3E=-5 or x%3C=3