Question

What is the instantaneous rate of change at `x=-4` if `f(x) = -9x^(2) -x`?

Answer 1

Instantaneous rate of change `= ((dy)/(dx))_(x=-4)`

`y = −9x^2−x`
`(dy)/(dx) = 2*(-9x)-x`
`= -18x-1`
`=> ((dy)/(dx))_(x=-4) = -18(-4)-1`
`= 72-1`
`= 71`

Answer 2

Instantaneous rate of change `= ((dy)/(dx))_(x=-4)`

`y = −9x^2−x`
`(dy)/(dx) = 2*(-9x)-x`
`= -18x-1`
`=> ((dy)/(dx))_(x=-4) = -18(-4)-1`
`= 72-1`
`= 71`