Slope of Secant Line Joining & More

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stephanie953

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Dec 14, 2006
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Hello. My one math problem is really stumping me.

Y=f(x) = x^2 + x

(A) Find the slope of the secant line joining (1,f(1)) and (3,f(3)).
(B) Find the slope of the secant line joining (1,f(1)) and (1+h,f(1+h)).
(C) Find the slope of the tangent line at (1,f(1)).
(D) Find the equation of the tangent line at (1,f(1))

I believe C you take the derivative of x^2 + x which is 2x + 1 which makes the slope 2(1) + 1 = 3

Otherwise I am completely lost on A, B, and D. Someone please help. Thank you.
 
stephanie953 said:
Hello. My one math problem is really stumping me.

Y=f(x) = x^2 + x

(A) Find the slope of the secant line joining (1,f(1)) and (3,f(3)).
(B) Find the slope of the secant line joining (1,f(1)) and (1+h,f(1+h)).
(C) Find the slope of the tangent line at (1,f(1)).
(D) Find the equation of the tangent line at (1,f(1))

I believe C you take the derivative of x^2 + x which is 2x + 1 which makes the slope 2(1) + 1 = 3

Otherwise I am completely lost on A, B, and D. Someone please help. Thank you.
Click to expand...

(A)

find f(1) = ???

find f(3) = ???

If a line passes through (x[sub:u45s1b74]1[/sub:u45s1b74],y[sub:u45s1b74]1[/sub:u45s1b74]) and (x[sub:u45s1b74]2[/sub:u45s1b74],y[sub:u45s1b74]2[/sub:u45s1b74]) then the slope of the line is:

\(\displaystyle m \, = \, \frac{y_2-y_1}{x_2-x_1}\)

This you should have learned and tatooed in your brain in high school algebra.
 
Oh jeez. Sometimes I over think things when they should be really simple. Sorry guys. Still not sure on D.
 
stephanie953 said:
This is what I have.
A) 5 <<<< correct
B) 3 + h <<<< correct
C) 3<<<< correct
D) y= 3x-1<<<< correct

Are these all correct?
Click to expand...
 
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