SAT Math : Algebra

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #12 : Algebraic Fractions

Which of the following provides the complete solution set for  ?

Possible Answers:

No solutions

Correct answer:

Explanation:

The absolute value will always be positive or 0, therefore all values of z will create a true statement as long as . Thus all values except for 2 will work.

Example Question #1 : How To Find Excluded Values

If the average (arithmetic mean) of , , and  is , what is the average of , , and ?

Possible Answers:

There is not enough information to determine the answer.

Correct answer:

Explanation:

If we can find the sum of \dpi{100} \small x+2, \dpi{100} \small y-6, and 10, we can determine their average. There is not enough information to solve for \dpi{100} \small x or \dpi{100} \small y individually, but we can find their sum, \dpi{100} \small x+y

Write out the average formula for the original three quantities.  Remember, adding together and dividing by the number of quantities gives the average: \frac{x + y + 9}{3} = 12

Isolate \dpi{100} \small x+y

x + y + 9 = 36

x + y = 27

 

Write out the average formula for the new three quantities: 

\frac{x + 2 + y - 6 + 10}{3} = ?

Combine the integers in the numerator:

\frac{x + y + 6}{3} = ?

Replace \dpi{100} \small x+y with 27:

\frac{27+ 6}{3} = \frac{33}{3} = 11

Example Question #2 : How To Find Excluded Values

Find the excluded values of the following algebraic fraction

Possible Answers:

The numerator cancels all the binomials in the denomniator so ther are no excluded values.

Correct answer:

Explanation:

To find the excluded values of a algebraic fraction you need to find when the denominator is zero. To find when the denominator is zero you need to factor it. This denominator factors into 

so this is zero when x=4,7 so our answer is 

Example Question #2 : How To Find Excluded Values

For what value(s) of x is the function undefined?  

Possible Answers:

Correct answer:

Explanation:

When the denominator of a function is equal to 0, the function is undefined at that point. We can set x2-25 equal to 0 in order to find out what values of x make that true. 

We can factor to solve for x. 

 

 is an incorrect answer because for this value of x, the function equals zero, but it is not undefined. 

Example Question #2 : How To Find Excluded Values

Find the extraneous solution for 

Possible Answers:

There are no extraneous solutions

Correct answer:

Explanation:

 

Now lets plug these values into our original equation.

 

For 

So this isn't an extraneous solution.

 

For 

Since  is an extraneous solution.

 

 

 

Example Question #1 : Distributive Property

Possible Answers:

Correct answer:

Explanation:

Example Question #1 : How To Use Foil In The Distributive Property

If , what is the value of ?

Possible Answers:

Correct answer:

Explanation:

Remember that (a – b )(a b ) = a 2 – b 2.

We can therefore rewrite (3x – 4)(3x + 4) = 2 as (3x )– (4)2 = 2.

Simplify to find 9x– 16 = 2.

Adding 16 to each side gives us 9x2 = 18.

Example Question #2 : How To Use Foil In The Distributive Property

If  and , then which of the following is equivalent to ?

Possible Answers:

Correct answer:

Explanation:

We are asked to find the difference between g(h(x)) and h(g(x)), where g(x) = 2x2 – 2 and h(x) = x + 4. Let's find expressions for both.

g(h(x)) = g(x + 4) = 2(x + 4)2 – 2

g(h(x)) = 2(x + 4)(x + 4) – 2

In order to find (x+4)(x+4) we can use the FOIL method.

(x + 4)(x + 4) = x2 + 4x + 4x + 16

g(h(x)) = 2(x2 + 4x + 4x + 16) – 2

g(h(x)) = 2(x2 + 8x + 16) – 2

Distribute and simplify.

g(h(x)) = 2x2 + 16x + 32 – 2

g(h(x)) = 2x2 + 16x + 30

Now, we need to find h(g(x)).

h(g(x)) = h(2x2 – 2) = 2x2 – 2 + 4

h(g(x)) = 2x2 + 2

Finally, we can find g(h(x)) – h(g(x)).

g(h(x)) – h(g(x)) = 2x2 + 16x + 30 – (2x2 + 2)

= 2x2 + 16x + 30 – 2x2 – 2

= 16x + 28

The answer is 16x + 28.

Example Question #2 : How To Use Foil In The Distributive Property

The sum of two numbers is . The product of the same two numbers is . If the two numbers are each increased by one, the new product is . Find  in terms of .

Possible Answers:

Correct answer:

Explanation:

Let the two numbers be x and y.

xy s

xyp

(x + 1)(y + 1) = q

Expand the last equation:

xyxy + 1 = q

Note that both of the first two equations can be substituted into this new equation:

ps + 1 = q

Solve this equation for q – p by subtracting p from both sides:

s + 1 = q – p

Example Question #5 : Distributive Property

Expand the expression:

\dpi{100} \small (x^{3}-4x)(6 + 12x^{2})

Possible Answers:

\dpi{100} \small 12x^{5}-42x^{3}-24x

\dpi{100} \small 6x^{3} + 12x^{5}-24x-48x^{3}

\dpi{100} \small 22x^{2}

\dpi{100} \small 42x^{3}+12x^{5}-24x

\dpi{100} \small 6x^{3} + 12x^{2}-24x-48

Correct answer:

\dpi{100} \small 12x^{5}-42x^{3}-24x

Explanation:

When using FOIL, multiply the first, outside, inside, then last expressions; then combine like terms.

\dpi{100} \small (x^{3}-4x)(6 + 12x^{2})

\dpi{100} \small 6x^{3}+12x^{5}-24x-48x^{3}

\dpi{100} \small -42x^{3}+12x^{5}-24x

\dpi{100} \small 12x^{5}-42x^{3}-24x

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