PSAT Math : How to factor a common factor out of squares

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #3 : Squaring / Square Roots / Radicals

x2 = 36

Quantity A: x

Quantity B: 6

Possible Answers:

Quantity B is greater

The relationship cannot be determined from the information given

The two quantities are equal

Quantity A is greater

Correct answer:

The relationship cannot be determined from the information given

Explanation:

x2 = 36 -> it is important to remember that this leads to two answers. 

x = 6 or x = -6. 

  If x = 6: A = B.

  If x = -6: A < B.

Thus the relationship cannot be determined from the information given.

Example Question #2 : How To Factor A Common Factor Out Of Squares

According to Heron's Formula, the area of a triangle with side lengths of a, b, and c is given by the following:

Hero

where s is one-half of the triangle's perimeter. 

 

What is the area of a triangle with side lengths of 6, 10, and 12 units?

Possible Answers:

14√2

4√14

8√14

12√5

48√77

Correct answer:

8√14

Explanation:

We can use Heron's formula to find the area of the triangle. We can let a = 6, b = 10, and c = 12.

In order to find s, we need to find one half of the perimeter. The perimeter is the sum of the lengths of the sides of the triangle.

Perimeter = a + b + c = 6 + 10 + 12 = 28

In order to find s, we must multiply the perimeter by one-half, which would give us (1/2)(28), or 14.

Now that we have a, b, c, and s, we can calculate the area using Heron's formula. 

Hero

Hero2

 

 

Example Question #171 : Exponents

Simplify the radical expression.

Possible Answers:

Correct answer:

Explanation:

Look for perfect cubes within each term. This will allow us to factor out of the radical.

Simplify.

Example Question #3 : How To Factor A Common Factor Out Of Squares

Simplify the expression.

Possible Answers:

Correct answer:

Explanation:

Use the distributive property for radicals. 

Multiply all terms by .

Combine terms under radicals.

Look for perfect square factors under each radical.  has a perfect square of . The can be factored out.

Since both radicals are the same, we can add them.

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