(base area)*h
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Well, it goes 5 inches per second so after 4 seconds it is 4 times 5 =20 inches under the surface, add that to 5 feet and you get 6 ft and 8 inches
(a) mtan refers to the slope of the tangent line. Given <em>f(x)</em> = 9 + 7<em>x</em> ², compute the difference quotient:

Then as <em>h</em> approaches 0 - bearing in mind that we're specifically considering <em>h</em> <em>near</em> 0, and not <em>h</em> = 0 - we can eliminate the factor of <em>h</em> in the numerator and denominator, so that

and so the slope of the line at <em>P</em> (0, 9), for which we take <em>x</em> = 0, is 0.
(b) The equation of the tangent line is then <em>y</em> = 9.
Answer: Estimates vary, but each person uses about 80-100 gallons of water per day
Okay, so the equation for the y-intercept is y=mx+b, this will be your base for graphing anything.
For y = x + 3 it's basically y = 1x + 3. Use b as the y-intercept, or 3, and plot it as (x,y), (0,3). Then use m as the slope, or 1. 1 means positive one so the point goes (0,3), (1, 4), (2, 5).
For y = -3x - 1 it's the same thing but different numbers. Use b, the y-intercept, and plot it. -1 is b, so plot (0,-1). Then use the slope to go up or down the direction you need to go, or m. m is -3, so for every +1 in x, the y will decrease by 3. (0,-1), (0,-4), (0,-7).
I hope this helped in some way or increased your understanding!