CAHSEE Math Algebra I: Drill 5, Problem 5. Which of the following is the solution set of this equation?
|Algebra||Systems of Equations|
|Algebra I||Polynomials and word problems|
|CAHSEE Math||Algebra I|
|Systems of Equations||Graphing|
so we know it can be solved by factoring.
That is, the answer is going to be of the format “x plus or minus something”…
with parentheses around it… times the same thing, also plus or minus.
So start with the x’s here and here with the parentheses around ‘em.
Now we need a 2 and a 5 on either end – we could have figured that out because we need
them to multiply out to be 10 and the only factors of 10 are 1 and 10 and 2 and 5…
…and since the middle term has a 3 in it, it can’t be 1 minus 10 or 10 minus 1.
So it’s either 2 or 5.
And we also know that one term has to be positive and one has to be negative because we need
a NEGATIVE 10 on the end there.
We need a POSITVE 3… so the 5 has to be positive and the 2 negative.
Now we’ve got the quantity x minus 2 times the quantity x plus 5.
And our answer is B.