Let's start by factoring out the . Then, we will factor the resulting .
Factor Out the Greatest Common Factor
The greatest common factor is a common factor of all the terms in the expression. It is the common factor with the greatest and the greatest . In this case, the greatest common factor is
x2.
2x4+7x3+5x2
x2⋅2x2+x2⋅7x+x2⋅5
x2(2x2+7x+5)
The result of factoring out the greatest common factor from the given expression is a with a of
2.
x2(2x2+7x+5)
Let's temporarily only focus on the expression in parentheses, and bring back the greatest common factor after factoring.
Factor the Quadratic Trinomial
Here we have a quadratic of the form ax2+bx+c, where ∣a∣=1 and there are no common factors. To factor this expression, we will rewrite the middle term, bx, as two terms. The coefficients of these two terms will be factors of ac whose sum must be b.
2x2+7x+5
We have that a=2, b=7, and c=5. There are now three steps we need to follow in order to rewrite the above expression.
- Find ac. Since we have that a=2 and c=5, the value of ac is 2×5=10.
- Find factors of ac. Since ac=10, which is positive, we need factors of ac to have the same sign — both positive or both negative — in order for the product to be positive. Since b=7, which is also positive, those factors will need to be positive so that their sum is positive.
1st factor-222nd factor-55Sum-2+(-5)2+5Result-77
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Rewrite bx as two terms. Now that we know which factors are the ones to be used, we can rewrite bx as two terms. 2x2+7x+5⇔2x2+2x+5x+5
Finally, we will factor the last expression obtained.
2x2+2x+5x+5
2x(x+1)+5x+5
2x(x+1)+5(x+1)
(x+1)(2x+5)
We have factored the quadratic trinomial.
2x2+7x+5⇔(x+1)(2x+5)
Finally, we need to include the greatest common factor that we factored out at the beginning.
2x4+7x3+5x2⇔x2(x+1)(2x+5)