Assume that f(x) is differentiable at x=a.state the equation of tangent line to the graph of f(x) at point (a,f(a))
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Originally Posted by bobby77 Assume that f(x) is differentiable at x=a.state the equation of tangent line to the graph of f(x) at point (a,f(a)) The equation of a line is y = mx + b We know the slope of the function at (a, f(a)): it is simply f'(a). Thus f(a) = f'(a)*a + b b = f(a) - f'(a)*a So y = f'(a)x + [f(a) - f'(a)*a] -Dan
You can also use the formula, If m is slope and (x_0,y_0) is point then equation is, y-y_0=m(x-x_0) Thus, m=f'(a) x_0=a y_0=f(a) Thus, y=f'(a)x-f'(a)a+f(a)
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