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slope of the tangent line?
Find the slope of the tangent line to the curve x^3 + 2xy + y^2 and find the equation of the line tangent to the curve at (1,1)
something is missing , it should read x^3 + 2xy + y^2 = 4
4 Answers
- 1 decade agoFavorite Answer
i agree with the above answer that, as written, this problem can't be solved. but i do assume that this is a typical calculus problem where the expression given is equal to a constant. to solve for the slope, the first derivative must be found:
d/dx (x^3+2xy+y^2) = d/dx (constant)
3x^2+2y+2x*dy/dx+2y*dy/dx = 0
dy/dx = (-3x^2-2y)/(2x+2y)
plug in x=1 and y=1:
dy/dx = (-3-2)/(2+2) = -5/4
using (1,1) and y=mx+b:
1 = (-5/4)(1) + b
b = 9/4
thus the equation of the line is y = -5/4x + 9/4
- MsMathLv 71 decade ago
x^3 + 2xy + y^2 = 4
Take the derivative of each side with respect to x.
You will have
3x^2 + 2y + 2xy' + 2yy' = 0
Move the terms with y' to the right side.
3x^2 + 2y = -2xy' - 2yy'
Factor out y' on the right side
3x^2 + 2y = y'(-2x - 2y)
Divide both sides by -2x-2y
y' = (3x^2 +2y)/(-2x-2y)
Now plug in your values for the point (1,1). That is, x =1 and y =1
y' = (3+2)/(-2-2)
y' = 5/-4
y' = -5/4
This is your slope.
Now use the equation
y - y1 = m(x-x1), where m is the slope and (x1,y1) is the given point.
y - 1 = (-5/4)(x-1)
- hfshawLv 71 decade ago
Either something is missing, or one of the "plus" signs in your expression should be an equals sign. As written,, "x^3 + 2xy + y^2" is not an equation (it's missing an equals sign).
The question cannot be answered as written.
- 4 years ago
if i remember properly all you're able to desire to do is discover the deverative. as quickly as you do, in simple terms plug in 2 and thats the slope as for a manner....i kinda forgot, its been a year, sorry all i remember is that e^x is chain rule, and ln x is a million/x