Step-by-step ExampleDetermine AC. In 3x� + 4x - 4, A = 3, B = 4, C = -4. ...Find two numbers whose sum is B and product is AC. Call the smaller number M and the larger number N. ...Rewrite the original equation as Ax� + Mx + Nx + C. ...Factor the new equation by grouping. ...Perform final factoring.