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Factoring trinomials

Factoring trinomials-example-1
User Zalun
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c^2
2c^2 + 13c +21 \\4c^2 + 13(2)c + 42\\(2c + 6)(2c+7)\\(c+3)(2c+7)


This is a way to factoring trinomials (there exist different equivalent methods).

Multiply the trinomial but the term accompanying
c^2. This is the second line. Then, you could take the square of the
4c^2, ant try to create a factor () () that will correspond to the expression in the second line. That is, we want
4c^2 + 13(2) c + 42 = (2c + ?) (2c + ?)

In ? we put the corresponding numbers that, if we multiply them we will obtain 42, and if we add them we will obtain 13. This numbers are 6 and 7. Then, we have
(2c + 6) (2c +7)

The last step is divide by the number that we multipy in the first step.

User SDBot
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