Suppose y = 2x + 1 where x and y are functions of t.
(a) If dx/dt = 6, find dy/dt when x = 4.
(b) If dy/dt = 4, find dx/dt when x = 40.

Question

Suppose y = 2x + 1 where x and y are functions of t.
(a) If dx/dt = 6, find dy/dt when x = 4.
(b) If dy/dt = 4, find dx/dt when x = 40.

anonymous · Answer

Can you do implicit differentiation?

aum · Answer

$$
y = 2x + 1 \
\frac{dy}{dt} = 2\frac{dx}{dt} + 0  \
a) \frac{dx}{dt} = 6.  ~~\text{Sub above and find }\frac{dy}{dt}
$$

anonymous · Answer

so then its 12?

anonymous · Answer

my online hw is saying thats the wrong answer

adamaero · Answer

with implicit diff. ...which is sad that I have to review at my level in Calculus

adamaero · Answer

http://dufu.math.ncu.edu.tw/calculus/calculus_bus/img539.gif

aum · Answer

$$
y = 2x + 1 \
\frac{dy}{dx} = 2 = \large \frac{\frac{dy}{dt}}{\frac{dx}{dt}}\
\frac{dy}{dt} = 2\frac{dx}{dt}  \
a) \frac{dx}{dt} = 6 \
\frac{dy}{dt} = 2 * 6 = 12 \
b) \frac{dy}{dt} = 4 \
\frac{dx}{dt} = 4/2 = 2 \
$$IDK why it is saying it is wrong.

aum · Answer

By any chance is $\large y = 2^x + 1$ instead of $\large y = 2x +1 $ ?