新SAT官方Daily Practice每日一题数学(9.14)

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摘要:本系列将给大家带来SAT官方的每日一题数学真题,各题型都有,持续更新,希望大家同步多练习。今天这里分享的是9月14日的数学,要继续加油练习哦~

Mathematics>Standard Multiple Choice


Read the following question and then select the best answer.

14q2+8pq-9p2+40pq-70q2+17p2

Which of the following is equivalent to the above expression?

A:-40p2q2+48pq

B:110p2q2+48pq

C: 8(p+7q)(p-q)

D: 8(p2+48pq-56q2)

Answer C


EXPLANATION

Choice C is correct. First, notice that some of the answer choices given are polynomials in standard form and some are in factored form. Start by combining like terms and then determine if the resulting polynomial can be factored.

Like terms in a polynomial are terms that have the same variable part raised to the same power. Combine the like terms in the above expression to obtain the following polynomial.

14q2+8pq-9p2+40pq-70q2+17p2

=(14q2-70q2)+(8pq+40pq)+( -9p2+17p2)

=-56q2+8p2+48pq

Since this is not an answer choice, determine if the polynomial can be factored.

=-56q2+8p2+48pq

=8(p2+6pq-7q2)

The equivalent expression is

=8(p+7q)(p-q)


难度系数:容易

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