How do you factor #x²+8x+7#?

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Answer 1 · 2015-11-07T23:14:33

#(x+1)(x+7)#

To quickly factor it, we want to find two numbers that add up to #8# (the coefficient in front of x) and multiply to #7# (the constant).

You might quickly see that the numbers we want are #1# and #7#.

Next, simply write 2 pairs of parenthesis and put "#x+#" and the two magical numbers we just found...

#(x+1)(x+7)#

Notice if you were to FOIL this out, you would get the original expression. In fact, what we just did was FOIL-ing backwards.

Answer 2 · 2015-11-07T23:14:45

#x^2+8x+7=(x+1)(x+7)#

#x^2+8x+7#

Find two numbers that when added equal #8# and when multiplied equal #7#. The numbers #1# and #7# meet the criteria.

#x^2+8x+7=(x+1)(x+7)#