Factoring, completing the square and setting a quadratic equal to zero are the main tools for Polynomials and quadratic equations.
Completing the square rests on one fact: adding the square of half the x coefficient makes a perfect square trinomial, so x squared plus six x becomes x plus three, squared, once nine is added. Pattern questions sometimes describe two quantities growing at different rates and ask when they match, which leads to a quadratic with one sensible positive root.
A well-known misconception is dividing both sides by x and losing a solution. Conditions like x being a positive integer often appear in quantitative comparisons.
Sample questions
Pick an answer to see whether it is right — nothing is saved, and nothing needs an account.
Question 1Easier
In a tile pattern, Figure n has n2 white tiles and 3n+10 gray tiles. For which value of n does the figure have the same number of white and gray tiles?
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Answer: B — 5
The counts are equal when n2=3n+10. Testing the choices, n=5 gives 25 white tiles and 3(5)+10=25 gray tiles.
Question 2Mid
x is a positive integer.
Column A
Column B
(x+4)(x−4)
xx3−16x
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Answer: C — The two quantities are equal
Column A expands to x2−16. In Column B, dividing each term by x gives x2−16 as well (valid since x>0), so the two are equal.
Question 3Easier
Which constant should be added to x2+10x so that the result is a perfect square trinomial?
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Answer: D — 25
Completing the square uses (210)2=25, and x2+10x+25=(x+5)2.
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