Q. 1. (8 pts) Using implicit differentiation, find dy/dx for the curve2cos(4x3)sin(7y)=−5x
Differentiate Left Side: To find dxdy using implicit differentiation, we need to differentiate both sides of the equation with respect to x, treating y as a function of x (y=y(x)). The equation is 2cos(4x3)sin(7y)=−5x.
Apply Product Rule: Differentiate the left side of the equation with respect to x. We will use the product rule, which states that the derivative of a product of two functions is the derivative of the first function times the second function plus the first function times the derivative of the second function. We also need to use the chain rule for each function.
Differentiate Right Side: Differentiating 2cos(4x3) with respect to x gives us −2×3×4x2×sin(4x3) because the derivative of cos(u) with respect to u is −sin(u), and we then multiply by the derivative of the inside function 4x3, which is 12x2.
Equate Derivatives: Differentiating sin(7y) with respect to x gives us 7cos(7y)⋅dxdy because the derivative of sin(u) with respect to u is cos(u), and we then multiply by the derivative of the inside function 7y with respect to x, which is 7⋅dxdy.
Isolate Term for dxdy: Now we apply the product rule: the derivative of 2cos(4x3)sin(7y) with respect to x is (−24x2⋅sin(4x3))⋅sin(7y)+2cos(4x3)⋅(7cos(7y)⋅dxdy).
Simplify Equation: Differentiate the right side of the equation with respect to x, which is −5x. The derivative of −5x with respect to x is −5.
Divide by Constants: Now we equate the derivatives from both sides of the equation: (−24x2⋅sin(4x3))⋅sin(7y)+2cos(4x3)⋅(7cos(7y)⋅dxdy)=−5.
Divide by Constants: Now we equate the derivatives from both sides of the equation: (−24x2⋅sin(4x3))⋅sin(7y)+2cos(4x3)⋅(7cos(7y)⋅dxdy)=−5.We need to solve for dxdy. To do this, we isolate the term containing dxdy on one side of the equation. This gives us 2cos(4x3)⋅(7cos(7y)⋅dxdy)=5−(−24x2⋅sin(4x3))⋅sin(7y).
Divide by Constants: Now we equate the derivatives from both sides of the equation: (−24x2⋅sin(4x3))⋅sin(7y)+2cos(4x3)⋅(7cos(7y)⋅dxdy)=−5.We need to solve for dxdy. To do this, we isolate the term containing dxdy on one side of the equation. This gives us 2cos(4x3)⋅(7cos(7y)⋅dxdy)=5−(−24x2⋅sin(4x3))⋅sin(7y).Simplify the equation to solve for dxdy: 14cos(4x3)cos(7y)⋅dxdy=5+24x2⋅sin(4x3)⋅sin(7y).
Divide by Constants: Now we equate the derivatives from both sides of the equation: (−24x2⋅sin(4x3))⋅sin(7y)+2cos(4x3)⋅(7cos(7y)⋅dxdy)=−5.We need to solve for dxdy. To do this, we isolate the term containing dxdy on one side of the equation. This gives us 2cos(4x3)⋅(7cos(7y)⋅dxdy)=5−(−24x2⋅sin(4x3))⋅sin(7y).Simplify the equation to solve for dxdy: 14cos(4x3)cos(7y)⋅dxdy=5+24x2⋅sin(4x3)⋅sin(7y).Finally, divide both sides by 14cos(4x3)cos(7y) to get dxdy on its own: dxdy=14cos(4x3)cos(7y)5+24x2⋅sin(4x3)⋅sin(7y).
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