Math

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1) A helium balloon is rising according to the function H(t) = -7x^2 + 5x - 11 where h(t) is the height in meters after t seconds. Determine the average rates of increase of height from t=7 to t=23 seconds.

I tried
h(23) - h(7)
------------
23-7

= * in this step i subbed it into the equation.

= -3599 + 319
-------------
16

It seems odd...

2) What is the end behaviour of
f(x) = 2-3x+4x^2
-----------
8x^2+5x-11

I understand end behaviour..but can someone help rearrange the first equation?

3) 2^2x - 4 (2^x) + 3 = 0
Solve for x.
This one I don't get at all.

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