Use the method of completing the square to solve x2-8x+7=0

Cassie is traveling 675 miles today to visit her brother and his family. so far, she has stopped for gas three times. at the first stop, she put in 7.1 gallons of gas and paid $23.79. at her second stop, she put in 5.8 gallons of gas and paid $19.08. and, at the third stop, 6.6 gallons and paid $20.39. at which stop did casey pay the most for gas?

The legs of a right triangle measure 6 meters and 8 meters. what is the length of the hypotonuse.

Which expression is equivalent to 64 - 9x^2?