SAT II Math II : Mathematical Relationships

Study concepts, example questions & explanations for SAT II Math II

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Example Questions

Example Question #7 : Properties And Identities

Which expression is not equal to 0 for all positive values of \displaystyle x?

Possible Answers:

All four expressions given in the other choices are equal to 0 for all positive values of \displaystyle x.

\displaystyle -x + x

\displaystyle \left (x+1 \right )^{0}

\displaystyle 0 (x+1)

\displaystyle 0^{x}

Correct answer:

\displaystyle \left (x+1 \right )^{0}

Explanation:

\displaystyle \left (x+1 \right )^{0} is the correct choice.

\displaystyle 0 (x+1) = 0 for all values of \displaystyle x, since, by the zero property of multiplication, any number multiplied by 0 yields product 0.

\displaystyle -x + x = 0 for all values of \displaystyle x - this is a direct statement of the inverse property of addition.

\displaystyle 0^{x} = 0, since 0 raised to any positive power yields a result of 0. 

\displaystyle \left (x+1 \right )^{0} = 1, since any nonxero number raised to the power of 0 yields a result of 1.

Example Question #1 : Ratios And Proportions

Solve the proportion:  \displaystyle \frac{2x+3}{2} = \frac{1}{3}

Possible Answers:

\displaystyle \frac{7}{6}

\displaystyle -\frac{7}{6}

\displaystyle -1

\displaystyle 2

\displaystyle -\frac{1}{6}

Correct answer:

\displaystyle -\frac{7}{6}

Explanation:

To solve the proportion, cross multiply the terms.

\displaystyle 3(2x+3) = 1(2)

\displaystyle 6x+9 = 2

Subtract 9 on both sides.

\displaystyle 6x+9 -9= 2-9

\displaystyle 6x=-7

Divide by 6 on both sides.

\displaystyle \frac{6x}{6}=\frac{-7}{6}

The answer is:  \displaystyle -\frac{7}{6}

Example Question #72 : Mathematical Relationships

Solve the ratio:  \displaystyle \frac{5}{9} = \frac{x}{6}

Possible Answers:

\displaystyle \frac{54}{5}

\displaystyle \frac{10}{3}

\displaystyle \frac{3}{10}

\displaystyle \frac{11}{9}

\displaystyle \frac{5}{54}

Correct answer:

\displaystyle \frac{10}{3}

Explanation:

To solve the proportion, cross multiply.

\displaystyle 5(6) = 9x

\displaystyle 30=9x

Divide by 9 on both sides.

\displaystyle \frac{30}{9}=\frac{9x}{9}

Reduce the fractions.

The answer is:  \displaystyle \frac{10}{3}

Example Question #1 : Ratios And Proportions

Determine the value of \displaystyle x:  \displaystyle \frac{2x-2}{8} = \frac{8x-2}{3}

Possible Answers:

\displaystyle -\frac{11}{29}

\displaystyle -\frac{1}{3}

\displaystyle -\frac{5}{29}

\displaystyle \frac{5}{29}

\displaystyle -\frac{5}{4}

Correct answer:

\displaystyle \frac{5}{29}

Explanation:

Cross multiply the fractions.

\displaystyle 3(2x-2) = 8(8x-2)

Simplify both sides.

\displaystyle 6x-6 = 64x-16

Subtract \displaystyle 6x on both sides.

\displaystyle 6x-6 -(6x)= 64x-16-(6x)

\displaystyle -6 = 58x-16

Add 16 on both sides.

\displaystyle -6+16 = 58x-16+16

\displaystyle 10= 58x

Divide by 58 on both sides.

\displaystyle \frac{10}{58}= \frac{58x}{58}

Reduce both fractions.

The answer is:  \displaystyle x = \frac{5}{29}

Example Question #1 : Ratios And Proportions

Solve the proportion:  \displaystyle \frac{x}{3} = \frac{2}{5}

Possible Answers:

\displaystyle 1

\displaystyle \frac{15}{2}

\displaystyle 0

\displaystyle \frac{6}{5}

\displaystyle \frac{5}{2}

Correct answer:

\displaystyle \frac{6}{5}

Explanation:

Cross multiply both sides.

\displaystyle 5x = 2(3)

Simplify and solve for x.

\displaystyle 5x=6

\displaystyle \frac{5x}{5}=\frac{6}{5}

The answer is:  \displaystyle \frac{6}{5}

Example Question #1 : Ratios And Proportions

Solve the proportion:  \displaystyle \frac{3x}{5} = \frac{1}{3}

Possible Answers:

\displaystyle \frac{5}{6}

\displaystyle \frac{5}{9}

\displaystyle 5

\displaystyle \frac{2}{3}

\displaystyle \frac{3}{2}

Correct answer:

\displaystyle \frac{5}{9}

Explanation:

Cross multiply both sides.

\displaystyle 3(3x) = 1(5)

\displaystyle 9x=5

Divide by 9 on both sides.

\displaystyle \frac{9x}{9}=\frac{5}{9}

The answer is:  \displaystyle \frac{5}{9}

Example Question #2 : Ratios And Proportions

Solve the proportion:  \displaystyle \frac{3x}{4} = \frac{8}{3}

Possible Answers:

\displaystyle \frac{9}{2}

\displaystyle \frac{2}{9}

\displaystyle \frac{1}{2}

\displaystyle 2

\displaystyle \frac{32}{9}

Correct answer:

\displaystyle \frac{32}{9}

Explanation:

Cross multiply the two fractions.

\displaystyle 3(3x) = 8(4)

\displaystyle 9x=32

Divide by nine on both sides.

\displaystyle \frac{9x}{9}=\frac{32}{9}

The answer is:  \displaystyle \frac{32}{9}

Example Question #2 : Ratios And Proportions

Solve the proportion:  \displaystyle \frac{2x}{9} = \frac{7}{3}

Possible Answers:

\displaystyle \frac{14}{3}

\displaystyle \frac{3}{2}

\displaystyle \frac{6}{7}

\displaystyle \frac{21}{2}

\displaystyle \frac{7}{6}

Correct answer:

\displaystyle \frac{21}{2}

Explanation:

Cross multiply the two fractions.

\displaystyle (2x)(3) = (7)(9)

\displaystyle 6x = 63

Divide by six on both sides.

\displaystyle \frac{6x }{6}= \frac{63}{6}

The answer is:  \displaystyle \frac{21}{2}

Example Question #1 : Matrices

Multiply:

\displaystyle \begin{bmatrix} x&7 \\ y& 3 \end{bmatrix}\begin{bmatrix} 2\\ 7 \end{bmatrix}

Possible Answers:

\displaystyle \begin{bmatrix}2 x&7 \\7 y& 3 \end{bmatrix}

\displaystyle \begin{bmatrix} 2x+49\\ 2y+21 \end{bmatrix}

\displaystyle \begin{bmatrix} 2x+7y\\ 35 \end{bmatrix}

\displaystyle \begin{bmatrix}2 x&14 \\7 y& 21 \end{bmatrix}

\displaystyle \begin{bmatrix}98x\\ 42y\end{bmatrix}

Correct answer:

\displaystyle \begin{bmatrix} 2x+49\\ 2y+21 \end{bmatrix}

Explanation:

The product of a 2 x 2 matrix and a 2 x 1 matrix is a 2 x 1 matrix.

Multiply each row in the first matrix by the column matrix by multiplying elements in corresponding positions, then adding the products, as follows:

\displaystyle \begin{bmatrix} x&7 \\ y& 3 \end{bmatrix}\begin{bmatrix} 2\\ 7 \end{bmatrix}

\displaystyle =\begin{bmatrix} x \cdot 2+ 7 \cdot 7 \\ y \cdot 2 + 3 \cdot 7 \end{bmatrix}\

\displaystyle =\begin{bmatrix} 2x + 49 \\ 2 y+ 21 \end{bmatrix}

Example Question #2 : Matrices

Multiply:

\displaystyle \begin{bmatrix} x& 5\\ -4& 3 \end{bmatrix}\begin{bmatrix} 6\\ y \end{bmatrix}

Possible Answers:

\displaystyle \begin{bmatrix} 30xy \\ -72y \end{bmatrix}

\displaystyle \begin{bmatrix} 6x+5y \\ 3y-24 \end{bmatrix}

\displaystyle \begin{bmatrix} 6x-4y \\ 3y+30 \end{bmatrix}

\displaystyle \begin{bmatrix}6 x&30\\ -4y& 3 y\end{bmatrix}

\displaystyle \begin{bmatrix}6 x&5\\ -4y& 3 \end{bmatrix}

Correct answer:

\displaystyle \begin{bmatrix} 6x+5y \\ 3y-24 \end{bmatrix}

Explanation:

The product of a 2 x 2 matrix and a 2 x 1 matrix is a 2 x 1 matrix.

Multiply each row in the first matrix by the column matrix by multiplying elements in corresponding positions, then adding the products, as follows:

\displaystyle \begin{bmatrix} x& 5\\ -4& 3 \end{bmatrix}\begin{bmatrix} 6\\ y \end{bmatrix}

\displaystyle = \begin{bmatrix} x \cdot 6 + 5\cdot y \\ -4\cdot 6 + 3 \cdot y \end{bmatrix}

\displaystyle = \begin{bmatrix} 6x+5y \\ 3y-24 \end{bmatrix}

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