Expand and simplify (x-5)(3x+3)
Begin by expanding brackets using FOIL (first, outer, inner, last) method (demonstrated on whiteboard to make clear). Multiplying the first term of each bracket gives 3x2, multiplying outer terms gives 3x, multiplying the inner terms gives -5x, and multiplying the last term of each bracket gives -15. Therefore we have 3x2+3x-5x-15. Collecting like terms and simplifying gives us 3x2-2x-15.
