Find an equation for the tangent line to the specified graph at the point given.
the graph of y=x^2 at (4, 16).
I need detailed explaination because I am just not following. Thanks
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OpenStudy (anonymous):
your graph is a parabola that runs through the origin, at the point (4,16) we want to find the equation of the tangent line y=mx+b
OpenStudy (anonymous):
because the line is tangent to our graph the slope of the tangent line and the slope at the point on our graph are equal
OpenStudy (anonymous):
take the derivative of the graph and plug in the value of x to find the slope at that point
OpenStudy (anonymous):
y'=2x evaluated at 4 = 8
OpenStudy (anonymous):
\[m=\frac{y1-y}{x1-x}=\frac{16-y}{4-x}\]
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OpenStudy (anonymous):
\[\frac{16-y}{4-x}=8\]
OpenStudy (anonymous):
16-y=8(4-x)
OpenStudy (anonymous):
how is that 8?
OpenStudy (anonymous):
16-32+8x=y and your equation is y=8x-16
OpenStudy (anonymous):
m is equal to slope and we no slope is y'=2(4)=8 so we can set them equal to each other
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OpenStudy (anonymous):
i dont under stand the inverse. it goes from y = x^2 to just 2x?
OpenStudy (anonymous):
thats the derivative of the function power rule
OpenStudy (anonymous):
d/dx x^n = nx^n-1
OpenStudy (anonymous):
oh yeah you bring it out front. ok sorry.
OpenStudy (anonymous):
its all good its a tricky question and tough to learn from a message board