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Hi there!

Can I also get some help with this one? #10 and #14. Please show your work. thanks! I'll do the rest :( ​

Hi there! Can I also get some help with this one? #10 and #14. Please show your work-example-1
User Yuk
by
6.8k points

1 Answer

3 votes

Hello from MrBillDoesMath!

Answer:

#10

y' = (2x - 3x^2)/(2y-1)

#14

y' = y^2/x^2

Discussion:

#10

x^2 + y = x^3 + y^2 (*)

Let y' be the first derivative of y with respect to x (i.e. dy/dx). Differentiating (*) gives

2x + y' = 3x^2 + 2yy' => subtract y' from both sides

2x = 3x^2 + 2yy' - y' => factor y' from the rhs

2x = 3x^2 + y' (2y - 1) => subtract 3x^2 from both sides

2x - 3x^2 = y'(2y-1) => divide both sides by (2y-1)

(2x - 3x^2)/(2y-1) = y'

#14

(1/x) + (1/y) = 1 (**)

Differentiating (**) gives

(-1/x^2) + ( -1 y^(-2)y') = 0 => as 1/x = x^(-1) and 1/y = y^(-1)

(-1/x^2) - y^(-2)y' = 0 => add y^(-2)y' to both sides

(-1/x^2) = y^(-2)y' => divide both sides by y^(-2)

(1/x^2)/ (y^(-2)) = y' => 1/(y^(-2)) = y^2

y^2/x^2 = y'

Thank you,

MrB

User Gagan Agrawal
by
5.9k points
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