SSAT Middle Level Math : Variables

Study concepts, example questions & explanations for SSAT Middle Level Math

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Example Questions

Example Question #4 : Algebra

Simplify:

 \displaystyle 2x + 15xy - 3x + 4y - 5xz + 4x

Possible Answers:

\displaystyle 15xy+4y-x-5xz

\displaystyle 3x + 4y + 15xy - 5xz

\displaystyle x+2xyz

\displaystyle 13xy+4y

Correct answer:

\displaystyle 3x + 4y + 15xy - 5xz

Explanation:

First, group together your like variables:

\displaystyle 2x + 4x - 3x + 4y + 15xy - 5xz

The only like variables needing to be combined are the x-variables.  You can do this in steps or all at once:

\displaystyle 2x + x + 4y + 15xy - 5xz

\displaystyle 3x + 4y + 15xy - 5xz

Example Question #31 : Variables

Simplify:

\displaystyle 20x + 3y - 14x + 12y - 4z - 2xy

Possible Answers:

\displaystyle 15xy

\displaystyle 6x+15y-16xy

\displaystyle 8x+4y+12xy

\displaystyle 6x + 15y - 4z - 2xy

Correct answer:

\displaystyle 6x + 15y - 4z - 2xy

Explanation:

First, move the like terms to be next to each other:

\displaystyle 20x - 14x + 3y + 12y - 4z - 2xy

Now, combine the x-variables and the y-variables:

\displaystyle 6x + 15y - 4z - 2xy

Example Question #155 : Operations

Simplify:

\displaystyle 14xy + x + 12yz + 15x + 3zy

Possible Answers:

\displaystyle 30xy +15yz

\displaystyle 14xy + 16x^{2} + 15y^{2}z^{2}

\displaystyle 14xy + 16x + 15yz

\displaystyle 30xy +12yz + 3zy

\displaystyle 14xy + 16x^{2} + 12yz + 3zy

Correct answer:

\displaystyle 14xy + 16x + 15yz

Explanation:

Let's begin by moving the like terms toward each other.  Notice the following: zy is the same as yz.  (Recall the commutative property of multiplication.)

\displaystyle 14xy + x + 15x + 12yz + 3yz

Now, all you have to do is combine the x-variables and the yz-terms:

\displaystyle 14xy + 16x + 15yz

Notice that you do not end up with any exponent changes.  That would only happen if you multiplied those variables.

Example Question #1211 : Hspt Mathematics

Simplify:

\displaystyle x^{2} + 5y^{4} + 3y^{2} + 15x^{2} + 12x^{2}y^{4}

Possible Answers:

\displaystyle 16x^{2} + 5y^{4} + 3y^{2} + 12x^{2}y^{4}

\displaystyle 3y^{2} + 33x^{2}y^{4}

\displaystyle 16x^{2} + 8y^{6} + 12x^{2}y^{4}

\displaystyle 18x^{2}y^{2} + 5y^{4} + 12x^{2}y^{4}

\displaystyle 36x^{24y^{10}

Correct answer:

\displaystyle 16x^{2} + 5y^{4} + 3y^{2} + 12x^{2}y^{4}

Explanation:

Remember, when you have exponents like this, you will treat each exponented variable as though it were its own "type."  Likewise, pairs of variables are to be grouped together.  Therefore, group the problem as follows:

\displaystyle (x^{2} + 15x^{2}) + 3y^{2} + 5y^{4} + 12x^{2}y^{4}

Notice that the only thing to be combined are the \displaystyle x^{2} terms.

Therefore, your answer will be:

\displaystyle 16x^{2} + 5y^{4} + 3y^{2} + 12x^{2}y^{4}

 

Example Question #1212 : Hspt Mathematics

Simplify:

\displaystyle 3x + 5x^{2} + 15xy + 12x^{2} + 4y^{2}

Possible Answers:

\displaystyle 20x^{2} + 15xy + 4y^{2}

\displaystyle 39x^{6}y^{3}

\displaystyle 18x + 5x^{2} + 15xy + 4y^{2}

\displaystyle 3x + 17x^{2} + 15xy + 4y^{2}

\displaystyle 39x^{2}y^{2}

Correct answer:

\displaystyle 3x + 17x^{2} + 15xy + 4y^{2}

Explanation:

Remember, for exponent problems, you group together different exponents and different combinations of variables as though each were a different type of variable.  Therefore, you can group your problem as follows:

\displaystyle 3x + (5x^{2} + 12x^{2})+ 15xy + 4y^{2}

Then, all you need to do is to combine the \displaystyle x^{2} terms:

\displaystyle 3x + (17x^{2})+ 15xy + 4y^{2}

Example Question #11 : How To Add Variables

Simplify:

\displaystyle 15x + 2x^{2} + 4(x + 22x^{2})

Possible Answers:

\displaystyle 19x + 24x^{2}

\displaystyle 109x^{3}

\displaystyle 33x^{3}

\displaystyle 109x^{2}

\displaystyle 19x + 90x^{2}

Correct answer:

\displaystyle 19x + 90x^{2}

Explanation:

Begin by distributing the \displaystyle 4 through the parentheses:

\displaystyle 15x + 2x^{2} + 4x + 88x^{2}

Next, move the like terms next to each other.  Remember, treat \displaystyle x^{2} like it is its own, separate variable.

\displaystyle 15x+ 4x + 2x^{2} + 88x^{2}

Finally, combine like terms:

\displaystyle 19x + 90x^{2}

Example Question #21 : How To Add Variables

Simplify:

\displaystyle x^3-2x-4x^3+3x^2+x+x^2

Possible Answers:

\displaystyle 3x^3+4x^2+x

\displaystyle -3x^3+4x^2-x

\displaystyle -5x^3+4x^2+3x

\displaystyle 5x^3+4x^2-3x

Correct answer:

\displaystyle -3x^3+4x^2-x

Explanation:

Combine like terms:

\displaystyle x^3+2x-4x^3+3x^2-x+x^2

\displaystyle =(x^3-4x^3)+(3x^2+x^2)+(-2x+x)

\displaystyle =-3x^3+4x^2-x

Example Question #22 : How To Add Variables

Simplify:

\displaystyle 7x^2+8x^3+9x^2-6x+2-4x^3

Possible Answers:

\displaystyle 4x^3+16x^2-6x+2

\displaystyle 6x^3+8x^2-3x+1

\displaystyle 2x^3+8x^2-3x+1

\displaystyle 12x^3+16x^2-6x+2

Correct answer:

\displaystyle 4x^3+16x^2-6x+2

Explanation:

Combine like terms:

\displaystyle 7x^2+8x^3+9x^2-6x+2-4x^3

\displaystyle =(8x^3-4x^3)+(7x^2+9x^2)-6x+2=4x^3+16x^2-6x+2

Example Question #32 : Variables

\displaystyle f (x) = 5x + 1

Evaluate \displaystyle f (-3)

Possible Answers:

\displaystyle -14

\displaystyle -16

\displaystyle -12

\displaystyle -18

Correct answer:

\displaystyle -14

Explanation:

\displaystyle f (x) = 5x + 1 

\displaystyle f (-3) = 5 (-3) + 1 = -15+1 = -14

Example Question #33 : Variables

\displaystyle 6r+3r+3r=

Possible Answers:

\displaystyle 108r

\displaystyle 9r

\displaystyle 12r

\displaystyle 24r

\displaystyle 0

Correct answer:

\displaystyle 12r

Explanation:

Add the numbers and keep the variable:

\displaystyle 6r+3r+3r=12r

Answer: \displaystyle 12r

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