How to expand double brackets?
Use the FOIL method, first, outside, inside, last. 1) F: The first term in the first bracket multiplies the first term in the second bracket. 2) O: The first term in the first bracket jumps outside to multiply the second term in the second bracket. 3) I: The second term in the first bracket multiplies the first term in the second bracket so the two 'inside' terms are multiplying together 4) L: The second term in the first bracket multiplies the second term in second bracket so both of the last terms are multiplying together EXAMPLEexpand: (X - 5) (X +2) = 0 1) X x X = X2 2) X x 2 = 2X 3) -5 x X = -5X 4) -5 x 2 = -10put it all together: X2 + 2X - 5X -10 =0 simplify: X2 -3X -10 = 0
