1. Find the equation of the tangent to:
a) u = x – 2x2 + 3 at x = 2
u1= 1 – 4x
Gradient = 1 – 4(2)
= - 7
The equation of a line is of the form y = mx + c , m is the gradient and c is the y intercept.
When x = 2,
y = 1 – 2(2 x2) + 3
y = 1 – 8 + 3
y = -4
Thus the equation of the tangent line will be given by,
Y = -7x + c substituting the point (2, -4) in the equation we have;
-4 = -7 x 2 + c
-4 + 14 = c
10 = c
y = -7x + 10
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