The roots of a function are the x-intercepts. By definition, the y-coordinate of points lying on the x-axis is zero. Therefore, to find the roots of a quadratic function, we set f (x) = 0, and solve the equation, ax2 + bx + c = 0.
One car 40 miles /gallon other car 30 miles/gallon .. Total miles = 165 gas used = 45 gallons ... let first car drive x miles second car drive y miles .. x/40 + y/30 = 45 (30x+40y)/30*40 = 45 30x+40y = 45*40*30 30x+40y=54,000
