SOLUTION: Find the Equation of a Tangent Line to f(x) = 3x^2 - 11x + 23 at the point (1,15)
I've worked out using the 1st derivative as hinted and would appreciate any checking if this is
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-> SOLUTION: Find the Equation of a Tangent Line to f(x) = 3x^2 - 11x + 23 at the point (1,15)
I've worked out using the 1st derivative as hinted and would appreciate any checking if this is
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Question 1048785: Find the Equation of a Tangent Line to f(x) = 3x^2 - 11x + 23 at the point (1,15)
I've worked out using the 1st derivative as hinted and would appreciate any checking if this is correct, many thanks.
1st derivative: d/dx [f(x)]
f'(x)= d/dx [3x^2 - 11x + 23]
=3* d/dx [x^2] - 11* d/dx [x] + d/dx [23] (using power rule)
=3*2x - 11*1 + 0
=6x - 11
Plug x=1 into f'(x)
f'(1) = 6(1) - 11
= -5
Using point-slope form
y-y1 = m(x-x1)
y-15 = -5(x-1)
y=-5x+5+15
Ans: y=-5x+20
