Answer:
150 cm/s
Step-by-step explanation:
We have that the area of a rectangle is as follows:
a = l * w
they ask us to change the increase in area with respect to time, therefore, if we derive with respect to t we are left with:
da / dt = w * (dl / d) t + l * (dw / dt)
From the statement we know that:
l = 20 cm
w = 15 cm
dl / dt = 6 cm / s
dw / dt = 3 cm / s
replacing each value we have:
da / dt = 15 * 6 + 20 * 3
da / dt = 150
Which means that 150 cm / s increases the area of the rectangle in relation to time
