Question

Given y = 3x − 4x, find dy. Evaluate dy at x = 4 and dx = 0.02.

Answer 1

y = x4 - 3x2 + x - 1

dy/dx = 4x3 - 6x + 1; dy = (4x3 - 6x + 1)dx

At x = 2, dx = 0.1

dy = [4(8) – 6(2) + 1] (0.1)

= (32 – 12 + 1) (0.1)

= (21) (0.1) = 2.1

dy = (4x3 – 6x + 1)dx; dy = 2.1