Consider the parabola y = 8x - x2. Find the slope of the tangent line to the parabola at the point (1, 7).
Solution:
Given, equation of parabola y = 8x - x2
Point (1, 7)
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’ = 8 - 2x
Substituting the point (1, 7) in the above equation,
y(1)’ = 8 - 2(1)
y(1)’ = 8 - 2 = 6
The equation of the line is given by
y - f(a) = f’(a) (x - a)
Now, y - 7 = 6 (x - 1)
y - 7 = 6x - 6
y = 6x - 6 + 7
y = 6x + 1
The equation of the tangent line is y = 6x + 1.
The above equation represents the slope-intercept form of a line y = mx + c
So, slope m = 6
Therefore, the slope of the tangent line is 6.
Consider the parabola y = 8x - x2. Find the slope of the tangent line to the parabola at the point (1, 7).
Summary:
The slope of the tangent line to the parabola y = 8x - x² at the point (1, 7) is 6.
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