2-1-8 seacant line
X
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Find an equation for the line tangent to Y equal -5 -, 3 X
squared at -3 negative 32.
So the first thing we need to do is we need to find the slope at
any given point of that equation Y equal -5 -, 3 X squared.
So I'm going to do this in a very generic fashion versus at
the specific point.
So if I wanted to do it for any point on the curve, we'd use our
limit as H goes to 0 of F of X + H -, F of X all over H.
So the limit as H goes to zero -5 - 3.
We're going to stick an X + H quantity squared there.
Then we're going to subtract the F of X, which is -5 -, 3 X
squared, and it's all going to go over H.
Now we're going to do a bunch of algebra and simplification.
So if we multiply the X + H ^2 quantity squared, we get X ^2 +
2 XH plus H ^2.
If we distribute the -3 in the next line, we get negative three
X ^2 -, 6 XH -3 H squared.
Then the -5 and +5 will cancel the -3 X squared and the +3 X
squared will cancel.
So when our numerator gets left -6 XH -3 H squared all over H,
if we factor an H out of that numerator, then we have an H
over HH in the numerator, H in the denominator.
That'll reduce to 1.
So we'd get the limit as H goes to 0 of -6 X -3 H if H was zero
-3 * 0 zero.
So we get -6 X -6 X is the secant slope for absolutely any
point on the given curve.
Now the fact that they gave us the point -3 negative 32, we're
going to actually find the sequence slope -6 X at that
point.
So I'm going to stick in -3 for the X and I get a slope of 18.
Now we're given a point and we're given a slope.
So we're going to use our point slope equation y - -32 equal 18
times the quantity X - -3.
We do our algebra for a final answer of Y equal eighteen X +
22.