What is the mean of 9 , 12 z and 15 stamps

The graph represents the gallons of water in a water tank with respect to the number of hours since it was completely filled

X-intercept=-5 y-intercept=2 the equation of the line is

Evaluate the discriminant of each equation. tell how many solutions each equation has and whether the solutions are real or imaginary. x^2 + 4x + 5 = 0