Find the set of values for x for which x^2 - 9x <= 36
Rearrange to get x^2 - 9x - 36 <= 0 Solve quadratic (x-12)(x+3) <= 0 Solve for x x = 12, x = -3
Now, we have key points 12 and -3, we need the range of values for x where x^2 - 9x - 36 <= 0.
So, we can visualise quadratic. It's positive, so the range of values lower than y=0 will be -3 < x < 12. This is the answer.
DD
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