SSAT Upper Level Math : Algebra

Study concepts, example questions & explanations for SSAT Upper Level Math

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Example Questions

Example Question #181 : Ssat Upper Level Quantitative (Math)

\(\displaystyle x> 0\) and \(\displaystyle y > 0\)

\(\displaystyle x^{2} = 8\)

\(\displaystyle y^{2} = 18\)

Evaluate \(\displaystyle (x+ y) ^{2}\).

Possible Answers:

\(\displaystyle 26\)

\(\displaystyle 144\)

\(\displaystyle 38\)

\(\displaystyle 50\)

Correct answer:

\(\displaystyle 50\)

Explanation:

By the perfect square trinomial pattern,

\(\displaystyle (x+ y) ^{2}\)

\(\displaystyle =x^{2} +2xy+ y ^{2}\)

\(\displaystyle x^{2} = 8\) and \(\displaystyle y^{2} = 18\).

Also, by the Power of a Power Principle, 

\(\displaystyle (xy) ^{2} = x^{2} y^{2} = 8 \cdot 18 = 144\)

so, since \(\displaystyle x\) and \(\displaystyle y\) are both positive, 

\(\displaystyle xy = \sqrt{(xy) ^{2} }= \sqrt{144}= 12\).

Therefore, 

\(\displaystyle (x+ y) ^{2}\)

\(\displaystyle =x^{2} +2xy+ y ^{2}\)

\(\displaystyle = 8 +2 (12)+18\)

\(\displaystyle = 8 +24 +18\)

\(\displaystyle = 50\)

 

Example Question #181 : Algebra

\(\displaystyle y^{3} = -17\)

\(\displaystyle y^{9} = ?\)

Possible Answers:

\(\displaystyle 51\)

\(\displaystyle -4,913\)

\(\displaystyle -51\)

\(\displaystyle 4,913\)

Correct answer:

\(\displaystyle -4,913\)

Explanation:

By the Power of a Power Principle, 

\(\displaystyle (y ^{3} ) ^{3} = y ^{3 \cdot 3} = y ^{9}\)

Therefore, we substitute, keeping in mind that an odd power of a negative number is also negative:

\(\displaystyle y ^{9} = (y ^{3} ) ^{3}\)

\(\displaystyle = (-17) ^{3}\)

\(\displaystyle = - 17 ^{3}\)

\(\displaystyle = - (17 \cdot 17\cdot 17)\)

\(\displaystyle = -4,913\)

Example Question #183 : Ssat Upper Level Quantitative (Math)

\(\displaystyle x> 0\) and \(\displaystyle y > 0\)

\(\displaystyle x^{2} = 18\)

\(\displaystyle y^{2} = 8\)

Evaluate \(\displaystyle (x- y) ^{2}\).

Possible Answers:

\(\displaystyle 10\)

\(\displaystyle 50\)

\(\displaystyle 2\)

\(\displaystyle 26\)

Correct answer:

\(\displaystyle 2\)

Explanation:

By the perfect square trinomial pattern,

\(\displaystyle (x- y) ^{2}\)

\(\displaystyle =x^{2} -2xy+ y ^{2}\)

\(\displaystyle x^{2} =1 8\) and \(\displaystyle y^{2} = 8\).

Also, by the Power of a Power Principle, 

\(\displaystyle (xy) ^{2} = x^{2} y^{2} = 18 \cdot 8 = 144\)

so, since \(\displaystyle x\) and \(\displaystyle y\) are both positive,

\(\displaystyle xy = \sqrt{(xy) ^{2} }= \sqrt{144}= 12\).

Therefore, 

\(\displaystyle (x- y) ^{2}\)

\(\displaystyle =x^{2} -2xy+ y ^{2}\)

And, substituting:

\(\displaystyle x^{2} -2xy+ y ^{2}\)

\(\displaystyle =18 -2 (12)+8\)

\(\displaystyle =18 -24 +8\)

\(\displaystyle = 2\)

Example Question #184 : Ssat Upper Level Quantitative (Math)

\(\displaystyle t^{6} = 144\)

\(\displaystyle x^{6}= 81\)

\(\displaystyle t > 0, x< 0\)

Evaluate the expression \(\displaystyle (t-x) (t^{2}+tx+x^{2})\).

Possible Answers:

\(\displaystyle 21\)

\(\displaystyle -21\)

\(\displaystyle 3\)

\(\displaystyle -3\)

Correct answer:

\(\displaystyle 21\)

Explanation:

Multiply out the expression by using multiple distributions and collecting like terms:

\(\displaystyle (t-x) (t^{2}+tx+x^{2})\)

\(\displaystyle = t (t^{2}+tx+x^{2}) - x (t^{2}+tx+x^{2})\)

\(\displaystyle = t \cdot t^{2}+ t \cdot tx+ t \cdot x^{2} - x \cdot t^{2}- x \cdot tx- x \cdot x^{2}\)

\(\displaystyle = t^{3}+ t^{2} x+ t x^{2} - t^{2} x- tx^{2} - x^{3}\)

\(\displaystyle = t^{3}+ t^{2} x- t^{2} x + t x^{2} - tx^{2} - x^{3}\)

\(\displaystyle = t^{3} - x^{3}\)

Since \(\displaystyle (t^{3} ) ^{2} = t ^{3 \cdot 2 } = t^{6}\) by the Power of a Power Principle,

\(\displaystyle t^{3} = \pm \sqrt{ t^{6}} = \pm \sqrt{144} = \pm 12\).

However, \(\displaystyle t\) is positive, so \(\displaystyle t^{3}\) is as well, so we choose \(\displaystyle t^{3} = 12\).

Similarly, 

\(\displaystyle x^{3} = \pm \sqrt{x^{6}} = \pm \sqrt{81} = \pm 9\).

However, since \(\displaystyle x\) is negative, as an odd power of a negative number, \(\displaystyle x^{3}\) is as well, so we choose \(\displaystyle x^{3} = -9\).

Therefore, substituting:

\(\displaystyle (t-x) (t^{2}+tx+x^{2}) = t^{3} - x^{3} = 12 - (-9) = 21\) 

Example Question #181 : Algebra

\(\displaystyle A\) and \(\displaystyle B\) are both positive integers; A is odd. What can you say about the number 

\(\displaystyle (A + B + 1)^{A+B+1}\) ?

Possible Answers:

\(\displaystyle (A + B + 1)^{A+B+1}\) is odd if \(\displaystyle B\) is odd, and even if \(\displaystyle B\) is even.

\(\displaystyle (A + B + 1)^{A+B+1}\) is even if \(\displaystyle B\) is odd, and odd if \(\displaystyle B\) is even.

\(\displaystyle (A + B + 1)^{A+B+1}\) is even if \(\displaystyle B\) is even, and can be odd or even if \(\displaystyle B\) is odd.

\(\displaystyle (A + B + 1)^{A+B+1}\) is odd if \(\displaystyle B\) is odd, and can be odd or even if \(\displaystyle B\) is even.

\(\displaystyle (A + B + 1)^{A+B+1}\) is even if \(\displaystyle B\) is odd, and can be odd or even if \(\displaystyle B\) is even.

Correct answer:

\(\displaystyle (A + B + 1)^{A+B+1}\) is odd if \(\displaystyle B\) is odd, and even if \(\displaystyle B\) is even.

Explanation:

If \(\displaystyle B\) is odd, then \(\displaystyle A + B +1\), the sum of three odd integers, is odd; an odd number taken to any positive integer power is odd.

If \(\displaystyle B\) is even, then \(\displaystyle A + B +1\), the sum of two odd integers and an even integer, is even; an even number taken to any positive integer power is even. 

Therefore, \(\displaystyle (A + B + 1)^{A+B+1}\) always assumes the same odd/even parity as \(\displaystyle B\).

Example Question #181 : Algebra

Give the equation of a line that passes through the point \(\displaystyle (4,7)\) and has slope 1.

Possible Answers:

\(\displaystyle y = 7\)

\(\displaystyle x = 4\)

\(\displaystyle x + y = 11\)

\(\displaystyle x-y = 3\)

\(\displaystyle x-y = -3\)

Correct answer:

\(\displaystyle x-y = -3\)

Explanation:

We can use the point slope form of a line, substituting \(\displaystyle m = 1, x_{1} = 4, y _{1} = 7\).

\(\displaystyle y- y_{1} = m (x-x_{1})\)

\(\displaystyle y- 7 = 1 (x-4)\)

\(\displaystyle y- 7 = x-4\)

\(\displaystyle y- 7 -y +4 = x-4 -y +4\)

\(\displaystyle -3 = x-y\)

or 

\(\displaystyle x-y = -3\)

Example Question #182 : Algebra

A line can be represented by \(\displaystyle 2x+3y=6\). What is the slope of the line that is perpendicular to it?

Possible Answers:

\(\displaystyle \frac{3}{4}\)

\(\displaystyle -\frac{2}{3}\)

\(\displaystyle \frac{2}{3}\)

\(\displaystyle \frac{3}{2}\)

\(\displaystyle 2\)

Correct answer:

\(\displaystyle \frac{3}{2}\)

Explanation:

You will first solve for Y, to get the equation in \(\displaystyle y=mx+b\) form.

\(\displaystyle m\) represents the slope of the line, which would be \(\displaystyle -\frac{2}{3}\).

A perpendicular line's slope would be the negative reciprocal of that value, which is \(\displaystyle \frac{3}{2}\).

Example Question #182 : Algebra

Find the equation the line goes through the points \(\displaystyle (3,4)\) and \(\displaystyle (0,2)\).

Possible Answers:

\(\displaystyle y=-\frac{2}{3}x+2\)

\(\displaystyle y=-\frac{3}{2}x+2\)

\(\displaystyle y=\frac{2}{3}x+2\)

\(\displaystyle y=\frac{3}{2}x+2\)

Correct answer:

\(\displaystyle y=\frac{2}{3}x+2\)

Explanation:

First, find the slope of the line.

\(\displaystyle \text{Slope}=\frac{y_2-y_1}{x_2-x_1}=\frac{2-4}{0-3}=\frac{-2}{-3}=\frac{2}{3}\)

Now, because the problem tells us that the line goes through \(\displaystyle (0,2)\), our y-intercept must be \(\displaystyle 2\).

Putting the pieces together, we get the following equation:

\(\displaystyle y=\frac{2}{3}x+2\)

Example Question #3 : How To Find The Equation Of A Line

A line passes through the points \(\displaystyle (-4, 6)\) and \(\displaystyle (-2, -2)\). Find the equation of this line.

Possible Answers:

\(\displaystyle y=-4x-10\)

\(\displaystyle y=-\frac{1}{4}x+10\)

\(\displaystyle y=\frac{1}{4}x-8\)

\(\displaystyle y=4x+10\)

Correct answer:

\(\displaystyle y=-4x-10\)

Explanation:

To find the equation of a line, we need to first find the slope.

\(\displaystyle \text{Slope}=\frac{y_2-y_1}{x_2-x_1}=\frac{-2-6}{-2-(-4)}=\frac{-8}{2}=-4\)

Now, our equation for the line looks like the following:

\(\displaystyle y=-4x+b\)

To find the y-intercept, plug in one of the given points and solve for \(\displaystyle b\). Using \(\displaystyle (-4, 6)\), we get the following equation:

\(\displaystyle 6=-4(-4)+b\)

Solve for \(\displaystyle b\).

\(\displaystyle 6=16+b\)

\(\displaystyle b=-10\)

Now, plug the value for \(\displaystyle b\) into the equation.

\(\displaystyle y=-4x-10\)

Example Question #183 : Algebra

What is the equation of a line that passes through the points \(\displaystyle (8,1)\) and \(\displaystyle (-2, -7)\)?

Possible Answers:

\(\displaystyle y=\frac{4}{5}x-\frac{27}{5}\)

\(\displaystyle y=-\frac{4}{5}x+\frac{27}{5}\)

\(\displaystyle y=\frac{5}{4}x+\frac{32}{5}\)

\(\displaystyle y=\frac{27}{5}x-\frac{4}{5}\)

Correct answer:

\(\displaystyle y=\frac{4}{5}x-\frac{27}{5}\)

Explanation:

First, we need to find the slope of the line.

\(\displaystyle \text{Slope}=\frac{y_2-y_1}{x_2-x_1}=\frac{-7-1}{-2-8}=\frac{-8}{-10}=\frac{4}{5}\)

Next, find the \(\displaystyle y\)-intercept. To find the \(\displaystyle y\)-intercept, plug in the values of one point into the equation \(\displaystyle y=mx+b\), where \(\displaystyle m\) is the slope that we just found and \(\displaystyle b\) is the \(\displaystyle y\)-intercept.

\(\displaystyle 1=8(\frac{4}{5})+b\)

Solve for \(\displaystyle b\).

\(\displaystyle 1=\frac{32}{5}+b\)

\(\displaystyle b=-\frac{27}{5}\)

Now, put the slope and \(\displaystyle y\)-intercept together to get \(\displaystyle y=\frac{4}{5}x-\frac{27}{5}\)

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