SAT Math : Algebra

Study concepts, example questions & explanations for SAT Math

varsity tutors app store varsity tutors android store varsity tutors ibooks store

Example Questions

Example Question #8 : Rational Expressions

Evaluate and simplify the following product:

\(\displaystyle \frac{15x^2+4xy^3-3y}{x^2y^7}\times\frac{5y^4}{4x^3}\)

Possible Answers:

\(\displaystyle \frac{20x^2+9xy^3-2y}{4x^5y^3}\)

\(\displaystyle \frac{75x^2+20xy^3-15y}{4x^5y^3}\)

\(\displaystyle \frac{75x^6+20xy^1^2-15y^4}{4x^6y^3}\)

\(\displaystyle \frac{75x^2y^-^3+20x-15y}{4x^5}\)

Correct answer:

\(\displaystyle \frac{75x^2+20xy^3-15y}{4x^5y^3}\)

Explanation:

The procedure for multplying together two rational expressions is the same as multiplying together any two fractions: find the product of the numerators and the product of the denominators separately, and then simplify the resulting quotient as far as possible, as shown:

\(\displaystyle \frac{15x^2+4xy^3-3y}{x^2y^7}\times\frac{5y^4}{4x^3}\)

\(\displaystyle =\frac{(15x^2+4xy^3-3y)(5y^4)}{(x^2y^7)(4x^3)}\)

\(\displaystyle =\frac{75x^2y^4+20xy^7-15y^5}{4x^5y^7}\)

\(\displaystyle =\frac{75x^2+20xy^3-15y}{4x^5y^3}\)

Example Question #2 : Expressions

Simplify the following rational expression: (9x - 2)/(x2) MINUS (6x - 8)/(x2)

Possible Answers:

\(\displaystyle \frac{15x+6}{x}\)

\(\displaystyle 3x-10\)

\(\displaystyle \frac{3x+6}{x^{2}}\)

\(\displaystyle \frac{12x-6}{x}\)

Correct answer:

\(\displaystyle \frac{3x+6}{x^{2}}\)

Explanation:

Since both expressions have a common denominator, x2, we can just recopy the denominator and focus on the numerators. We get (9x - 2) - (6x - 8). We must distribute the negative sign over the 6x - 8 expression which gives us 9x - 2 - 6x + 8 ( -2 minus a -8 gives a +6 since a negative and negative make a positive). The numerator is therefore 3x + 6.

Example Question #1 : How To Add Rational Expressions With A Common Denominator

Simplify the following rational expression:

\(\displaystyle \frac{7x-18}{x^{2}}+\frac{6x-14}{x^{2}}\)

 

Possible Answers:

\(\displaystyle \frac{13x-28}{x^{2}}\)

\(\displaystyle \frac{x-32}{x^{2}}\)

\(\displaystyle \frac{x-4}{x^{2}}\)

\(\displaystyle \frac{13x-32}{x^{2}}\)

\(\displaystyle \frac{13x-4}{x^{2}}\)

Correct answer:

\(\displaystyle \frac{13x-32}{x^{2}}\)

Explanation:

Since both fractions in the expression have a common denominator of \(\displaystyle x^{2}\), we can combine like terms into a single numerator over the denominator:

\(\displaystyle \frac{7x-18}{x^{2}}+\frac{6x-14}{x^{2}}\)

\(\displaystyle =\frac{(7x-18)+(6x-14)}{x^{2}}\)

\(\displaystyle =\frac{13x-32}{x^{2}}\)

Example Question #1 : How To Add Rational Expressions With A Common Denominator

Simplify the following rational expression:

\(\displaystyle \frac{5x-5}{2x^{2}} + \frac{7x+9}{2x^{2}}\)

Possible Answers:

\(\displaystyle \frac{6x+8}{2x^{2}}\)

\(\displaystyle \frac{8x+4}{2x^{2}}\)

\(\displaystyle \frac{6x+4}{2x^{2}}\)

\(\displaystyle \frac{12x+8}{2x^{2}}\)

\(\displaystyle \frac{6x+2}{x^{2}}\)

Correct answer:

\(\displaystyle \frac{6x+2}{x^{2}}\)

Explanation:

Since both rational terms in the expression have the common denominator \(\displaystyle 2x^{2}\), combine the numerators and simplify like terms:

 

\(\displaystyle \frac{5x-5}{2x^{2}} + \frac{7x+9}{2x^{2}}\)

\(\displaystyle =\frac{(5x-5)+(7x+9)}{2x^{2}}\)

\(\displaystyle =\frac{12x+4}{2x^{2}}\)

\(\displaystyle =\frac{6x+2}{x^2}\)

Example Question #3 : Expressions

Simplify the following expression:

\(\displaystyle \frac{10x-9}{x^{3}}+\frac{11x+12}{x^{3}}\)

Possible Answers:

\(\displaystyle \frac{x+3}{x^{3}}\)

\(\displaystyle \frac{21x+3}{x^{3}}\)

\(\displaystyle \frac{21x-3}{x^3}\)

\(\displaystyle \frac{3-21x}{x^{3}}\)

\(\displaystyle \frac{3-x}{x^{3}}\)

Correct answer:

\(\displaystyle \frac{21x+3}{x^{3}}\)

Explanation:

Since both terms in the expression have the common denominator \(\displaystyle x^{3}\), combine the fractions and simplify the numerators:

\(\displaystyle \frac{10x-9}{x^{3}}+\frac{11x+12}{x^{3}}\)

\(\displaystyle =\frac{(10x-9)+(11x+12)}{x^{3}}\)

\(\displaystyle =\frac{21x+3}{x^{3}}\)

Example Question #1 : How To Evaluate Algebraic Expressions

A total of 150 million votes were tallied in a presidential election. Votes were cast for either Hillary Clinton, Rand Paul, Al Gore, or Gary Johnson. If Clinton received 3 times the number of votes as Johnson, Paul received 30% of the vote, and Gore receieved 30 million total votes, who received the most votes in the election?

Possible Answers:

Gary Johnson

Hillary Clinton

Rand Paul

Al Gore

Correct answer:

Hillary Clinton

Explanation:

There are a few ways to do this problem, but we will focus on the total number of votes method as follows. First, let Clinton = C, Gore = G, Paul = P, and Johnson = J. We know C + G + P + J = 150 million. We also know that C = 3J. Paul received 30% of the vote which is 150,000,000 * .3 = 45 million votes. Gore received 30 million votes. We can now create an equation with individual totals and substitute 3J for Clinton's vote total:

3J + 30 million + 45 million + J = 150 million

4J = 75 million

J = 18.75 million

Then C = 3J = 56.25 million. So Clinton received 56.25 million votes, Paul received 45 million votes, Gore received 30 million votes, and Johnson received 18.75 million votes.  The correct answer is Hillary Clinton.

Example Question #1 : Evaluating And Simplifying Expressions

Justin makes 61.9% of his free throws. During the season he had 84 free throw attempts.  How many of Jason’s shots did not go in?

Possible Answers:

52

21

40

36

32

Correct answer:

32

Explanation:

Find how many free throws Justin made:  84 x 0.619 = 51.99.  Since the problem talks free throws, we round to 52 shots went in.  To calculate shots missed:

84 – 52 = 32.

Example Question #1 : Evaluating And Simplifying Expressions

If 5x + 30 = 6 – 7x, then x = ?

Possible Answers:

x = –10

x = 2

x = –37

x = –2

x = –18

Correct answer:

x = –2

Explanation:

Combine like terms by subtracting 6 from both sides so:  5x + 24 = –7x.  Then subtract 5x from both sides:  24 = –12x.  Divide both sides by –12 and x = –2.

Example Question #1 : How To Evaluate Algebraic Expressions

If ab - bc + d = d2 - c2, then what is the value of a when b is two, c is negative one, and d is zero?

 

 

Possible Answers:
-3/2
-1
3/2
1/2
-1/2
Correct answer: -3/2
Explanation:

ab - bc + d = d2 - c2

We need to substitute values in for b, c, and d, and then solve the equation for a.

a(2) - 2(-1) + 0 = 02 - (-1)2

2a +2 + 0 = 0 - (1)

2a + 2 = -1

2a = -3

a = -3/2

The answer is -3/2.

Example Question #3 : Evaluating And Simplifying Expressions

If 11x + 4 = 19x – 12, then what is 2x – 4?

Possible Answers:

0

2

Not possible

4

–8

Correct answer:

0

Explanation:

First solve for x. The first equation would simplify as:

16 = 8x

x = 2

If we plug x = 2 into the second expression:

2(2) – 4 = 0 

0 is the correct answer.

Learning Tools by Varsity Tutors