Question

3x²- x - 4

middle term splitting

Answer 1

${3x}^{2} - x - 4 \\ = {3x}^{2} - (4 - 3) x - 4 \\ = {3x}^{2} - 4x + 3x - 4 \\ = x(3x - 4) + 1(3x - 4) \\ = (3x - 4)(x + 1)$

Answer 2

You should use formula -b+root(bsquare-4ac)dividedby2a and -b-root(bsquare-4ac)dividedby2a. You will get 2 values of x here a=3 b=1 and c=4