step 1:2x[3x2-20x+28] Factor out anything common to all terms.
step 2:2x[3x2+(-20)x+28] Write trinomial in sandard form ax2+bx+c
step 3:2x[3x2+(-20)x+28] Determine product of a･ｃ=3･28=84
step 4:List all pairs of factors of a･ｃ.If a･ｃ is negative,then factors have opposite signs.
If a･ｃ is positive,then factors have same signs.Sign of b determines sign of factors.
Factor of 84 are:-1,84 -4,-21 -6,-14 -7,-12
Select factor pair such that their sum is b term=-20
step 5:Sprit middle term b order factors as multiple of the a and c terms
step 6:Factor out something common to first two terms.
step 7:Factor out same binominal in last two terms.
step 8: Apply Distributive Law and convert trinomial into the product of two binomials and a monomial.
2x[(3x-14)(x-2)]→ 2x(3x-14)(x-2) This is the answer.