Ap Calc Acceleration, Velocity and Time

Question

A rectangle has a length of 6 inches and a width of 7 inches whose sides are changing. The length is increasing by 7 in/sec and the width is shrinking at 2 in/sec. What is the rate of change of the area?

Answer 1

A = lw; dA/dt = ldw/dt + wdl/dt = 6in·(- 2in/sec) + 7in·7in/sec = 37 in²/sec