PSAT Math : PSAT Mathematics

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #1201 : Psat Mathematics

Possible Answers:

Correct answer:

Explanation:

Example Question #1202 : Psat Mathematics

 

 

 

 

Rationalize the denominator:

Possible Answers:

Correct answer:

Explanation:

The conjugate of is  .

Now multiply both the numerator and the denominator by

and you get:

 

Hence we get

Example Question #1203 : Psat Mathematics

Solve for :

Possible Answers:

Correct answer:

Explanation:

 

Example Question #1204 : Psat Mathematics

Solve for .

Possible Answers:

Correct answer:

Explanation:

Example Question #1205 : Psat Mathematics

If,

 

What does

Possible Answers:

Correct answer:

Explanation:

If  ,

 then .

Example Question #16 : Exponents And Rational Numbers

Possible Answers:

Correct answer:

Explanation:

From the equation in the problem statement

Now squaring both sides we get

  this is a quadratic equation which equals

and the factors of this equation are

This gives us .

However, if we plug these solutions back into the original equation,   does not create an equality. Therefore,  is an extraneous solution.

 

Example Question #5 : How To Find A Rational Number From An Exponent

For some positive integer , if , what is the value of ?

Possible Answers:

Correct answer:

Explanation:

If , then  must equal 3 (Note that  cannot be -3 because you need it to be positive. 

Now, plug  into the new equation :

 

Example Question #551 : Algebra

Factor 2x2 - 5x – 12

Possible Answers:

(x – 4) (2x – 3)

(x + 4) (2x + 3)

(x - 4) (2x + 3)

(x + 4) (2x + 3)

Correct answer:

(x - 4) (2x + 3)

Explanation:

Via the FOIL method, we can attest that x(2x) + x(3) + –4(2x) + –4(3) = 2x2 – 5x – 12.

Example Question #111 : Exponents

x > 0.

Quantity A: (x+3)(x-5)(x)

Quantity B: (x-3)(x-1)(x+3)

Possible Answers:

Quantity A is greater

The two quantities are equal

The relationship cannot be determined from the information given

Quantity B is greater

Correct answer:

Quantity B is greater

Explanation:

 

Use FOIL: 

 

  (x+3)(x-5)(x) = (x2 - 5x + 3x - 15)(x) = x3 - 5x2 + 3x2 - 15x = x3 - 2x2 - 15x for A.

 

  (x-3)(x-1)(x+3) = (x-3)(x+3)(x-1) = (x2 + 3x - 3x - 9)(x-1) = (x2 - 9)(x-1)

  (x2 - 9)(x-1) = x3 - x2 - 9x + 9 for B. 

The difference between A and B: 

 (x3 - 2x2 - 15x) - (x3 - x2 - 9x + 9) = x3 - 2x2 - 15x - x3 + x2 + 9x - 9

 = - x2 - 4x - 9. Since all of the terms are negative and x > 0:

  A - B < 0.

Rearrange A - B < 0:

  A < B

 

 

 

Example Question #1206 : Psat Mathematics

Solve for all real values of .

Possible Answers:

Correct answer:

Explanation:

First, move all terms to one side of the equation to set them equal to zero.

All terms contain an , so we can factor it out of the equation.

Now, we can factor the quadratic in parenthesis. We need two numbers that add to and multiply to .

We now have three terms that multiply to equal zero. One of these terms must equal zero in order for the product to be zero.

Our answer will be .

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