To get this quadratic function in standard form we need to use a distribution method called FOIL. FOIL stands for First, Outer, Inner, Last. This is a way to keep yourself organized in distributing each number.
Step 1: Multiply the First terms in each parentheses
`4x * 4x = 16x^2`
Step 2: Multiply the Outer terms
`4x * -9 = -36x`
Step 3: Multiply the Inner terms
`9*4x = 36x`
Step 4: Multiply the Last terms in each parentheses
`9*-9 = -81`
Step 5: Now put the solutions together
`y=16x^2 -36x +36x -81`
Step 6: Combine like terms
We can use the foil method to solve this equation.
All together: `16x^2+36x-36x-81`