0.8 miles per hour
<span><span><u>THE WORK</u>
2 miles <span>÷ 2.5
</span></span><span>--------------
2.5 hours <span>÷ 2.5</span></span></span>
<span><span>=
0.8 miles
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</span>1 hour
</span><span><span>
</span></span>
Simply solve for x:
-x^2 + 9 = 0 => x = 3 and x = -3;
plug x = 3 and x = -3 into the original equation you get 3 = 3 and -9 = -9, respectively;
So, the two intersecting points are (-3, -9), (3, 3).
And of course, the parabola opens down since its square term is minus.
