What is this? e^(xy) + y^2 = sin(x + y)
my teacher gave me the hardest algebra question he found on yahoo because i can do almost every algebra question but he doesn't think so. !

Use the diagonals to determine whether a parallelogram with vertices u(2,−2), v(9,−2), w(9,−6), and x(2,−6) is a rectangle, rhombus, or square. give all the names that apply.

The amount spent on food and drink by 20 customers is shown below what is the modal amount spent and the median? 40 25 8 36 18 15 24 27 43 9 12 19 22 34 31 20 26 19 17 28

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.