SAT Math : SAT Mathematics

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #1 : Factoring Polynomials

When  is factored, it can be written in the form , where , , , , , and  are all integer constants, and .

What is the value of ?

Possible Answers:

Correct answer:

Explanation:

Let's try to factor x2 – y2 – z2 + 2yz.

Notice that the last three terms are very close to y2 + z2 – 2yz, which, if we rearranged them, would become y2 – 2yz+ z2. We could factor y2 – 2yz+ z2 as (y – z)2, using the general rule that p2 – 2pq + q2 = (p – q)2 .

So we want to rearrange the last three terms. Let's group them together first.

x2 + (–y2 – z2 + 2yz)

If we were to factor out a –1 from the last three terms, we would have the following:

x2 – (y2 + z2 – 2yz)

Now we can replace y2 + z2 – 2yz with (y – z)2.

x2 – (y – z)2

This expression is actually a differences of squares. In general, we can factor p2 – q2 as (p – q)(p + q). In this case, we can substitute x for p and (y – z) for q.

x2 – (y – z)= (x – (y – z))(x  + (y – z))

Now, let's distribute the negative one in the trinomial x – (y – z)

(x – (y – z))(x  + (y – z)) 

(x – y + z)(x + y – z)

The problem said that factoring x2 – y2 – z2 + 2yz would result in two polynomials in the form (ax + by + cz)(dx + ey + fz), where a, b, c, d, e, and f were all integers, and a > 0.

(x – y + z)(x + y – z) fits this form. This means that a = 1, b = –1, c = 1, d = 1, e = 1, and f = –1. The sum of all of these is 2.

The answer is 2. 

Example Question #2 : Factoring Polynomials

Factor and simplify:

\frac{64y^{2} - 16}{8y + 4}

Possible Answers:

8y

8y-4

-4

8y+4

8y-12

Correct answer:

8y-4

Explanation:

64y^{2} - 16 is a difference of squares.

The difference of squares formula is a^{2} - b^{2} = (a - b)(a + b).

Therefore, \frac{64y^{2} - 16}{8y + 4} = \frac{(8y + 4)(8y - 4)}{8y + 4} = 8y - 4.

Example Question #3 : Factoring Polynomials

Factor:

-12x^2+27

Possible Answers:

(2x+3)(2x+3)

(2x+3)(2x-3)

-3(2x+3)(2x+3)

-3(4x^{2}-9)

-3(2x+3)(2x-3)

Correct answer:

-3(2x+3)(2x-3)

Explanation:

We can first factor out -3:

-3(4x^{2}-9)

This factors further because there is a difference of squares:

-3(2x+3)(2x-3)

Example Question #6 : Factoring

A group of scientists form a global collective of temperature and climate data. U.S. temperature measurements are in Fahrenheit and must be converted to Celsius. If the average spring temperature for New York was  Fahrenheit, what is the temperature value in Celsius? 

The Fahrenheit to Celsius conversion equation is as follows:

Possible Answers:

 

Correct answer:

 

Explanation:

You can solve this problem by substituting in  for  and solving for :

That means that  Fahrenheit is the same as  Celsius.

Example Question #8 : Factoring

Factor to the simplest form:  

Possible Answers:

 

Correct answer:

 

Explanation:

Group all the terms with the  variable.

Pull out an  term from parentheses.

There are no more common factors.

The correct answer is:  

Example Question #7 : Factoring

A semi truck unloaded weighs . When the trailer compartment is loaded to half capacity with soda, the semi weighs . What will the truck weigh when the compartment is loaded to  capacity with the same kind of soda?

Possible Answers:

Correct answer:

Explanation:

This word problem can be broken down into a basic algebraic equation:

A half-loaded semi weighs 37,000 lbs. Subtracting the weight of the truck, we can determine that a half load weighs 17,000 lbs:

From that, we can determine that a full load = 34,000 lbs: 

Knowing the weight of a full load, we can calculate the weight of a 3/4 load:

Add the weight of the truck to get the total weight:

Example Question #1 : Exponents

If (300)(400) = 12 * 10n, n =

Possible Answers:

2

7

3

4

12

Correct answer:

4

Explanation:

(300)(400) = 120,000 or 12 * 104.

Example Question #2 : Exponents

(2x103) x (2x106) x (2x1012) = ?

Possible Answers:

8x1023

6x1023

6x1021

8x1021

Correct answer:

8x1021

Explanation:

The three two multiply to become 8 and the powers of ten can be added to become 1021.

Example Question #1 : Exponents

If 3x = 27, then 22x = ?

Possible Answers:

3

64

8

9

32

Correct answer:

64

Explanation:
  1. Solve for x in 3x = 27. x = 3 because 3 * 3 * 3 = 27.
  2. Since x = 3, one can substitute x for 3 in 22x 
  3. Now, the expression is 22*3
  4. This expression can be interpreted as 22 * 2* 22. Since 22 = 4, the expression can be simplified to become 4 * 4 * 4 = 64.
  5. You can also multiply the powers to simplify the expression. When you multiply the powers, you get 26, or 2 * 2 * 2 * 2 * 2 * 2
  6. 2= 64.

Example Question #2 : Exponential Operations

Find the value of x such that:

8x-3 = 164-x

Possible Answers:

4

19/4

7/2

11/3

25/7

Correct answer:

25/7

Explanation:

In order to solve this equation, we first need to find a common base for the exponents. We know that 23 = 8 and 24 = 16, so it makes sense to use 2 as a common base, and then rewrite each side of the equation as a power of 2.

8x-3 = (23)x-3

We need to remember our property of exponents which says that (ab)c = abc.

Thus (23)x-3 = 23(x-3) = 23x - 9.

We can do the same thing with 164-x.

164-x = (24)4-x = 24(4-x) = 216-4x.

So now our equation becomes

23x - 9 = 216-4x

In order to solve this equation, the exponents have to be equal. 

3x - 9 = 16 - 4x

Add 4x to both sides.

7x - 9 = 16

Add 9 to both sides.

7x = 25

Divide by 7.

x = 25/7.

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