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

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Answer 1 · 2015-03-29T06:49:04

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 · 2015-03-29T08:31:01

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

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

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