Math Study Strategies
Factoring Trinomials
ax2+ bx + c, when a=1
1st term of trinomial = (1st term of 1st binomial)(1st term of 2nd binomial)
last term of trinomial = (last term of 1st binomial)(last term of 2nd binomial)
Middle term the trinomi = (Product of outer terms of the binomials) + (Product of inner terms of the binomials)
If all terms of the trinomial are positive, then all terms of the binomials will
be
positive.
Ex 1
x2+ 9x + 8 = (x + 8)(x + 1)
If the last term of the trinomial is negative but the middle term and the first
term
are positive, then one term of the binomial will be negative and the other will
be
positive. (The greater factor will be positive and the smaller will be
negative.)
Ex 2
x2+ 7x - 30 = (x + 10)(x - 3)
If the middle term and the last term of the trinomial are negative and the first
term is positive, then the sign for one binomial will be positive and the
other will be negative. (The greater factor will be negative and the smaller
will be positive.)
Ex 3
x2- 6x - 40 = (x -10)(x + 4)
If the last term and the first term of the trinomial are positive but the middle
term is negative, then both signs of the binomials will be negative
Ex 4
x2- 11x + 18 = (x - 2)(x - 9)