How Do You Calculate the Rate of Area Increase in an Expanding Rectangle?

[ace123]

He is correct the dA/dt was not 70. If you look at coomast and his posts the reason he got his equation is by a^2(t ^2)+ b^2. Then plug in the numbers you have. L(t)=sqrt(4900t^2+2500)

 

[bondgirl007]

For my answer, I got 14700/sqrt(46600) and the back of my textbook has 1470/sqrt(466), which are both equivalent. I think I have it right.

 

[arildno]

For my answer, I got 14700/sqrt(46600) and the back of my textbook has 1470/sqrt(466), which are both equivalent. I think I have it right.

Indeed you do; problem solved