Question

URGENT HELP

Answer 1

Answer:

a = -6

b = 1

Step-by-step explanation:

The gradient of the tangent to the curve y = ax + bx^3, will be:

dy/dx = a + 3bx²

at (2, -4)

dy/dx = a+3b(2)²

dy/dx = a+12b

Since the gradient at the point is 6, then;

a+12b = 6 ....1

Substitute x = 2 and  y = -4 into the original expression

-4 = 2a + 8b

a + 4b = -2 ...2

a+12b = 6 ....1

Subtract

4b - 12b = -2-6

-8b = -8

b = -8/-8

b = 1

Substitute b = 1 into equation 1

Recall from 1 that a+12b = 6

a+12(1) = 6

a = 6 - 12

a = -6

Hence a = -6, b = 1