Find the absolute maximum and minimum values of function f on the set D f(x, y) = e^-x^2-y^2()x^2+2y^2; D is the disk x^2+y^2<=4

Use the elimination method to solve the system of equations -x+5y=-4 and 4x+3y=16

Jack has a piece of red ribbon that is two times as long as his piece of blue ribbon. he says that he can use two different equation to find out how long his piece of red ribbon is compared to his piece of blue ribbon is. is he correct? explain his reasoning

Out of $20$ creepy-crawly creatures in a room, $80\%$ are flies and $20\%$ are spiders. if $s\%$ of the total legs belong to spiders, what is $s$?