Q. Given that y=4x2−5, find dxd(3x5−3cosy) in terms of only x.Answer:
Find Derivative of 3x5: We need to find the derivative of the function 3x5−3cos(y) with respect to x. We will use the chain rule for the term involving y, since y is a function of x. First, let's find the derivative of 3x5 with respect to x. The derivative of xn with respect to x is 3x5−3cos(y)0, so the derivative of 3x5 is 3x5−3cos(y)2.
Derivative of −3cos(y): Now, let's find the derivative of −3cos(y) with respect to x. We will use the chain rule, which states that the derivative of a composite function is the derivative of the outer function evaluated at the inner function times the derivative of the inner function.The derivative of −3cos(y) with respect to y is 3sin(y), and we need to multiply this by the derivative of y with respect to x.
Derivative of y: We are given that y=4x2−5. Let's find the derivative of y with respect to x.The derivative of 4x2 with respect to x is 2⋅4x2−1=8x, and the derivative of a constant is 0, so the derivative of −5 is 0.Therefore, the derivative of y with respect to x is 8x.
Combine Derivatives: Now we can combine the derivatives we found. The derivative of 3x5−3cos(y) with respect to x is the derivative of 3x5 plus the derivative of −3cos(y) times the derivative of y with respect to x. This gives us 15x4−3sin(y)×8x.
Express in Terms of x: We need to express the derivative in terms of x only. We have the term −3sin(y)×8x, where y=4x2−5. We substitute y into the sine function to get −3sin(4x2−5)×8x.
Final Derivative: The final derivative of the function 3x5−3cos(y) with respect to x, expressed in terms of x only, is:15x4−24xsin(4x2−5).
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