Find the slope of the tangent line to the parabola y = 4x - x2 at the point (1, 3)
Solution:
Given, equation of parabola y = 4x - x2
Point (1, 3)
The tangent line to a curve is the one that coincides with the curve at a point and with the same derivative, i.e. the same degree of variation.
Differentiating the equation of parabola,
y’ = 4 - 2x
Substituting the point (1, 3) in the above equation,
y(1)’ = 4 - 2(1)
y(1)’ = 4 - 2 = 2
The equation of the line is given by
y - f(a) = f’(a) (x - a)
Now, y - 3 = 2 (x - 1)
y - 3 = 2x - 2
y = 2x - 2 + 3
y = 2x + 1
The equation of the tangent line is y = 2x + 1.
The above equation represents the slope-intercept form of a line y = mx + c
So, slope m = 2
Therefore, the slope of the tangent line is 2.
Find the slope of the tangent line to the parabola y = 4x - x2 at the point (1, 3)
Summary:
The slope of the tangent line to the parabola y = 4x - x2 at the point (1, 3) is 2.
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