Post

Created by @nathanedwards
 at November 4th 2023, 9:47:54 pm.

Question:

Consider the equation given by the implicit function:

x3+3xy25x=2y36xy+4 x^3 + 3xy^2 - 5x = 2y^3 - 6xy + 4

a) Find dydx\frac{{dy}}{{dx}} using implicit differentiation.

b) Determine the slope of the tangent line to the curve at the point (1,1)(1,1).

c) Find the equation of the tangent line to the curve at the point (1,1)(1,1).

Answer:

a) To find dydx\frac{{dy}}{{dx}} using implicit differentiation, we differentiate both sides of the equation with respect to xx and apply the chain rule.

Given equation: x3+3xy25x=2y36xy+4x^3 + 3xy^2 - 5x = 2y^3 - 6xy + 4

Differentiating both sides with respect to xx, we get:

ddx(x3+3xy25x)=ddx(2y36xy+4) \frac{{d}}{{dx}} \left( x^3 + 3xy^2 - 5x \right) = \frac{{d}}{{dx}} \left( 2y^3 - 6xy + 4 \right)

Using the chain rule and product rule on the left side, and the chain rule on the right side, we obtain:

3x2+3y2dydx+3y2dydx5=6y2dydx6xdydx 3x^2 + 3y^2 \cdot \frac{{dy}}{{dx}} + 3y^2 \cdot \frac{{dy}}{{dx}} - 5 = 6y^2 \cdot \frac{{dy}}{{dx}} - 6x \cdot \frac{{dy}}{{dx}}

Rearranging the terms, we have:

(3x2+6y26y2)dydx=5+6x3x2 (3x^2 + 6y^2 - 6y^2) \cdot \frac{{dy}}{{dx}} = -5 + 6x - 3x^2

Simplifying further, we obtain:

3x2dydx=6x3x2+5 3x^2 \cdot \frac{{dy}}{{dx}} = 6x - 3x^2 + 5

Finally, dividing both sides by 3x23x^2, we get the expression for dydx\frac{{dy}}{{dx}}:

dydx=2xx2+53x2 \frac{{dy}}{{dx}} = \frac{{2x - x^2 + \frac{5}{3}}}{{x^2}}

b) To find the slope of the tangent line to the curve at the point (1,1)(1,1), we substitute x=1x = 1 and y=1y = 1 into the expression dydx\frac{{dy}}{{dx}} we obtained above.

Substituting x=1x = 1 and y=1y = 1 into dydx\frac{{dy}}{{dx}} gives:

dydx=2(1)(1)2+53(1)2=831=83 \frac{{dy}}{{dx}} = \frac{{2(1) - (1)^2 + \frac{5}{3}}}{{(1)^2}} = \frac{{\frac{8}{3}}}{{1}} = \frac{8}{3}

Therefore, the slope of the tangent line to the curve at the point (1,1)(1,1) is 83\frac{8}{3}.

c) The equation of a line can be determined using the point-slope form yy1=m(xx1)y - y_1 = m(x - x_1), where (x1,y1)(x_1, y_1) is a point on the line and mm is the slope of the line.

Using the point (1,1)(1,1) and the slope 83\frac{8}{3}, we substitute these values into the point-slope form equation:

y1=83(x1) y - 1 = \frac{8}{3}(x - 1)

Multiplying both sides by 3 to eliminate the fraction, we get:

3y3=8(x1) 3y - 3 = 8(x - 1)

Expanding and rearranging, we obtain the equation of the tangent line:

8x3y5=0 8x - 3y - 5 = 0

Therefore, the equation of the tangent line to the curve at the point (1,1)(1,1) is 8x3y5=08x - 3y - 5 = 0.