Can someone please help me graphs this I don’t understand!

Write numerical coefficient of y² in the expression 2x² - 15xy – 7y²

The area of square garden is 300m squared. how long is the diagonal?

Adolphin is swimming with her friend. the dolphin jumps to a height of 4.54.54, point, 5 meters above the surface of the water as her friend swims 9.89.89, point, 8 meters directly below her. what is the position of the dolphin's friend relative to the surface of the water? meters