(a) Show that the function Let A=561 B=21 C=29 S(x, y)=(x2-1+(r-e") has two local minima but no other extreme points. (b) An environmental study finds that the average hottest day of the year in Country Z has been made significantly more intense because of deforestation since the start of the industrial revolution in the country. The study indicates that when Country Z has a forest cover of x km and a population of y million people, the average local temperature will be TC, where T (x, y) = 0.15/5x+ 2xy +37. The study further estimates that 7 years from now, there will be x() = A - 121 + 71 - 51 * + Bt km? of forest cover in Country Z, and the country's population will be BC yo- million people. Determine the rate at which the local temperature in B+C(0.8) Country Z is changing with respect to time 3 years from now. Give your answer correct to 3 significant figures. (Sustainable Development Goal 15: Life on Land) (a) Show that the function Let A=561 B=21 C=29 S(x, y)=(x2-1+(r-e") has two local minima but no other extreme points. (b) An environmental study finds that the average hottest day of the year in Country Z has been made significantly more intense because of deforestation since the start of the industrial revolution in the country. The study indicates that when Country Z has a forest cover of x km and a population of y million people, the average local temperature will be TC, where T (x, y) = 0.15/5x+ 2xy +37. The study further estimates that 7 years from now, there will be x() = A - 121 + 71 - 51 * + Bt km? of forest cover in Country Z, and the country's population will be BC yo- million people. Determine the rate at which the local temperature in B+C(0.8) Country Z is changing with respect to time 3 years from now. Give your answer correct to 3 significant figures. (Sustainable Development Goal 15: Life on Land)