PSAT Math : Algebra

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #71 : Algebra

 varies inversely as both the square of  and the square root of . Assuming that  does not depend on any other variable, which statement is true of  concerning its relationship to ?

Possible Answers:

 varies inversely as the fourth power of .

 varies directly as the fourth power of .

 varies inversely as .

 varies directly as the fourth root of .

 varies inversely as the fourth root of .

Correct answer:

 varies inversely as the fourth power of .

Explanation:

 varies inversely as both the square of  and the square root of , meaning that for some constant of variation ,

.

Square both sides, and the expression becomes

  takes the role of the new constant of variation here, and we now have

,

meaning that  varies inversely as the fourth power of .

Example Question #71 : Algebra

 varies directly as the square of  and inversely as  and . Assuming that  does not depend on any other variables, which of the following gives the variation relationship of  to  ?

Possible Answers:

 varies inversely as .

 varies directly as the fourth power of .

 varies inversely as the seventh power of .

 varies inversely as the fourth power of .

 varies directly as .

Correct answer:

 varies directly as .

Explanation:

 varies directly as the square of  and inversely as ; therefore, for some constant of variation ,

Setting  and , the formula becomes 

Setting  as the new constant of variation, we have a new variation equation

,

meaning that  varies directly as .

 

Example Question #1 : How To Multiply A Monomial By A Polynomial

If you have a rectangle with a width of  and a length of , what is the area of the rectangle?

Possible Answers:

Correct answer:

Explanation:

To find the area of a rectangle, multiply the length times the width.  Therefore, you must multiply  times .  To do that, you must multiply the monomial times each part of the trinomial, like so:

 

Example Question #2 : How To Multiply A Monomial By A Polynomial

Find the product:

Possible Answers:

Correct answer:

Explanation:

Use the distributive property:

Simplify: don't forget to use the rules of multiplying exponents (add them)

Example Question #3 : How To Multiply A Monomial By A Polynomial

Find the product:

Possible Answers:

Correct answer:

Explanation:

Find the product:

Use the distributive property:

When multiplying variables with exponents, add the exponents:

Example Question #1 : How To Multiply A Monomial By A Polynomial

Find the product:

Possible Answers:

Correct answer:

Explanation:

Find the product:

Use the distributive property:

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 #1 : 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 #4 : 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

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