Solve each system by graphing.

Describe the possible echelon forms of the standard matrix for a linear transformation t where t: set of real numbers is onto.

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?

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?