Verified answer

I won't solve, but I'll tell you how to do it.

For "A" the 4 is in the place of "t" in h(t) right? So just plug in 4 into all the "t" on the other side of the equation

For "B"- you know that 1 is January so 2 is February, 3 is March, and so on. Just keep plugging in the numbers for t until you get over 70.

For C- graph it on a calculator or you can do a(x-h)^2+k or you can complete the square, what is in the place of h and k will be the answer but the sign of h will be opposite in the answer. This website is great

http://www.algebralab.org/lessons/lesson.aspx?file...

Good Luck

h(4) = -1.5 * 4^2 + 21.6 * 4 - 3.2

= -1.5 * 16 + 86.4 - 3.2

= -24 + 86.4 - 3.2

= 59.2

**

70 = -1.5t^2 + 21.6t - 3.2

1.5t^2 - 21.6t + 73.2

15t^2 - 216t + 732 = 0

5t^2 - 72t + 244 = 0

t = (-(-72) +/- sqrt((-72)^2 - 4 * 5 * 244)) / (2 * 5)

t = (72 +/- sqrt(5184 - 4880)) / 10

t = (72 +/- sqrt(304)) / 10

t = (72 +/- sqrt(304)) / 10

t = (72 +/- 17.43) / 10

t = 89.43/10 or t = 55.43/10

t = 8.943 or t = 5.543

So we're talking the end of August or about halfway through May.

To find the vertex, take the derivative and set it to 0.

h'(t) = -3t + 21.6

-3t + 21.6 = 0

3t = 21.6

t = 7.2

The vertex is the time of highest temperature, which should be around the first weekend in July.