let the length be x inches
let the width by y inches
A = xy
dA/dt = x dy/dt + y dx/dt
for the given data...
dA/dt = 24(-3) + 15(4) = -12 inches^2/min
the area is decreasing at 12 square inches/min
P = 2x + 2y
dP/dt = 2 dx/dt + 2 dy/dt
= 2(-3) + 2(4) = 2 inches/min
A rectangle is 2 feet by 15 inches. Its length is decreasing by 3 inches/minute and its width is increasing at 4 inches/minute. How fast is the
a) perimeter changing
b) area changing
1 answer
1 answer