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Use the limit definition of the derivative to calculate the derivatives of the following functions.

a. f(x) = 2x²-3x+4
b. g(x) = =1/x² +1
c. h(x) = √3x-2

1 Answer

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Final answer:

a. f'(x) = 4x, b. g'(x) = 2/x - 2x, c. h'(x) = √3

Step-by-step explanation:

a. Derivative of f(x) = 2x²-3x+4

To find the derivative of f(x), we use the limit definition of the derivative. The limit definition is given as:

f'(x) = lim(h->0) (f(x+h) - f(x))/h

Substituting the given function into the limit definition:

f'(x) = lim(h->0) ((2(x+h)² - 3(x+h) + 4) - (2x² - 3x + 4))/h

Simplifying the expression:

f'(x) = lim(h->0) (2h² + 4xh)/(h)

Canceling out h:

f'(x) = lim(h->0) (2h + 4x)

Taking the limit as h approaches 0:

f'(x) = 4x

b. Derivative of g(x) = 1/x² + 1

To find the derivative of g(x), we again use the limit definition of the derivative:

g'(x) = lim(h->0) (g(x+h) - g(x))/h

Substituting the given function:

g'(x) = lim(h->0) (1/(x+h)² + 1 - (1/x² + 1))/h

Simplifying the expression:

g'(x) = lim(h->0) ((x² + xh + h² - x² - x²h - h² + x² + 2x + 1) - (1 + x²))/h

Canceling out h:

g'(x) = lim(h->0) (xh - x²h + 2x + 1)/h

Taking the limit as h approaches 0:

g'(x) = 2/x - 2x

c. Derivative of h(x) = √3x-2

Using the limit definition of the derivative:

h'(x) = lim(h->0) (h(x+h) - h(x))/h

Substituting the given function:

h'(x) = lim(h->0) (√3(x+h)-2 - (√3x-2))/h

Simplifying the expression:

h'(x) = lim(h->0) (√3x+√3h-2 - √3x+2)/h

Canceling out h:

h'(x) = lim(h->0) (√3h)/h

Taking the limit as h approaches 0:

h'(x) = √3

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