Pre-Algebra : Pre-Algebra

Study concepts, example questions & explanations for Pre-Algebra

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Example Questions

Example Question #31 : Polynomials

Simplify the polynomial.

\(\displaystyle 6x^2 + 2y + 4x + 3y -2x =\)

Possible Answers:

\(\displaystyle 10x^2 + 5y\)

\(\displaystyle 6x^2 + 6x + 5y\)

\(\displaystyle 8x^2 + 5y\)

\(\displaystyle 6x^2 + 5y + 2x\)

\(\displaystyle 6x^2 + 6y + 2x\)

Correct answer:

\(\displaystyle 6x^2 + 5y + 2x\)

Explanation:

When solving a polynomial you must combine like terms. Like terms have the same degree value. A degree value is the number of exponents a term has.

\(\displaystyle 6x^2 + 2y + 4x + 3y - 2x =\)

\(\displaystyle (6x^2) + (2y + 3y) + (4x - 2x) =\)

\(\displaystyle 6x^2 + 5y + 2x\)

Example Question #32 : Polynomials

Solve the following. 

\(\displaystyle (3x^2 -4x +2) + (2x^2 +9x-1)\)

Possible Answers:

\(\displaystyle 5x^4 - 5x +1\)

\(\displaystyle 5x^2 -5x +1\)

\(\displaystyle 5x^4 + 5x^2 +1\)

\(\displaystyle 5x^2 + 5x -1\)

\(\displaystyle 5x^2 + 5x + 1\)

Correct answer:

\(\displaystyle 5x^2 + 5x + 1\)

Explanation:

When adding polynomials, we simply look at each term and combine like terms. Like terms in this case are terms that have the same variables. 

\(\displaystyle (3x^2 -4x +2) + (2x^2 +9x-1)\)

We can remove the parentheses in the problem, because doing so will not change the order of operations. So, we get

\(\displaystyle 3x^2 -4x +2 + 2x^2 +9x-1\)

Now, we find like terms.

\(\displaystyle {\color{Red} 3x^2} {\color{Green} -4x} {\color{Blue} +2} {\color{Red}+ 2x^2} {\color{Green} +9x}{\color{Blue} -1}\)

You can see all like terms have been highlighted in different colors. Now, we can combine them.

\(\displaystyle {\color{Red} 3x^2 + 2x^2} = 5x^2\)

\(\displaystyle {\color{Green} -4x + 9x} = 5x\)

\(\displaystyle {\color{Blue} 2-1} = 1\)

Note that we only add the coefficients together. Ther variables themselves do not change.

Writing that together, we get 

\(\displaystyle 5x^2 + 5x +1\)

Example Question #33 : Polynomials

Simplify the following polynomials:

\(\displaystyle (2x+4y) + (6x-2y)\)

Possible Answers:

\(\displaystyle 8x+6y\)

\(\displaystyle 8x^2 + 2y^2\)

\(\displaystyle 12x-8y\)

\(\displaystyle 8x+2y\)

\(\displaystyle 8x^2+6y^2\)

Correct answer:

\(\displaystyle 8x+2y\)

Explanation:

To solve this problem, we will group and combine like terms.  We can remove the parentheses because they do not change the answer. We get

\(\displaystyle (2x+4y) + (6x-2y)\)

\(\displaystyle 2x + 4y + 6x - 2y\)

\(\displaystyle 2x + 6x + 4y - 2y\)

\(\displaystyle 8x + 2y\)

Note that when you combine like terms, the variables do not change.  We only combine the coefficients. 

Example Question #34 : Polynomials

Add the following polynomials:

\(\displaystyle (4x^2 - 2x - 4) + (9x^2 - 3x +1)\)

Possible Answers:

\(\displaystyle 13x^4 + 5x^2 + 3\)

\(\displaystyle 13x^2 - 5x - 3\)

\(\displaystyle 13x^2 - 5x + 3\)

\(\displaystyle 13x^2 + 5x +3\)

\(\displaystyle 13x^4 - 5x^2 - 3\)

Correct answer:

\(\displaystyle 13x^2 - 5x - 3\)

Explanation:

When adding polynomials, we can remove the parentheses because this does not have an effect on the answer. So,

\(\displaystyle (4x^2 - 2x - 4) + (9x^2 - 3x +1)\)

becomes

\(\displaystyle 4x^2 - 2x - 4 + 9x^2 - 3x +1\)

Now, we combine like terms.  Like terms are considered terms with the same variables.  So,

\(\displaystyle {\color{Red} 4x^2} {\color{Green} - 2x} {\color{Blue} - 4} {\color{Red} + 9x^2} {\color{Green} - 3x} {\color{Blue} +1}\)

where each different colored terms are like terms.  We combine them and get

\(\displaystyle {\color{Red} 13x^2} {\color{Green} - 5x} {\color{Blue} - 3}\)

Note that we do not change the variables when we add them, we only combine the coefficients.

Example Question #35 : Polynomials

Simplify the following expression:

\(\displaystyle (4x^3+3x^2)-(2x^3+8x^2)\)

Possible Answers:

\(\displaystyle 2x^3+11x^2\)

\(\displaystyle 2x^3-5x^2\)

\(\displaystyle 2x^3+5x^2\)

\(\displaystyle -6x^3\)

Correct answer:

\(\displaystyle 2x^3-5x^2\)

Explanation:

Simplify the following expression:

\(\displaystyle (4x^3+3x^2)-(2x^3+8x^2)\)

Let's begin by putting like terms next to eachother:

\(\displaystyle (4x^3-2x^3)+(3x^2-8x^2)\)

Next, we keep the exponents the same (because we are only adding/subtracting), but we treat the numbers out in front just like regular subtraction or addition.

\(\displaystyle (4x^3-2x^3)+(3x^2-8x^2)=2x^3-5x^2\)

So our answer is

\(\displaystyle 2x^3-5x^2\)

 

Example Question #36 : Polynomials

Simplify the following:

\(\displaystyle 4x^3+x^2-x^3+44=x^3\)

Possible Answers:

\(\displaystyle x^3+x^2+44=0\)

\(\displaystyle 3x^3+x^2+44=0\)

\(\displaystyle 2x^3+x^2+44=0\)

\(\displaystyle 4x^3+x^2+44=0\)

None of the above

Correct answer:

\(\displaystyle 2x^3+x^2+44=0\)

Explanation:

For this problem you need to combine your like terms.

\(\displaystyle 4x^3-x^3+x^2+44=x^3\)  simplifies to  \(\displaystyle 3x^3+x^2+44=x^3\)

 

But you must bring the other \(\displaystyle x^3\) over by subtraction so:

\(\displaystyle 2x^3+x^2+44=0\)

Example Question #37 : Polynomials

Combine like terms and simplify the polynomial.

\(\displaystyle (4p^{2}-4m)+(6p^{3}+6m-7v)\)

Possible Answers:

\(\displaystyle 6p^{3}-2m^{2}+4p^{2}-7v\)

\(\displaystyle 10p^{6}-2m^{2}-7v\)

\(\displaystyle 10p^{5}-2m^{2}-7v\)

\(\displaystyle 24p^{2}p^{3}+2m-7v\)

\(\displaystyle 6p^{3}+4p^{2}+2m-7v\)

Correct answer:

\(\displaystyle 6p^{3}+4p^{2}+2m-7v\)

Explanation:

When finding our answer the first step is to get rid of the parentheses symbol so we can combine like terms, so we start with the following equation:

\(\displaystyle (4p^{2}-4m)+(6p^{3}+6m-7v)\)

Then we have

\(\displaystyle 4p^{2}-4m+6p^{3}+6m-7v\)

We simple add like terms. Remember terms with the same power and variables can be added. So we have

\(\displaystyle 6p^{3}+4p^{2}+6m-4m-7v\)

The only term that will change from our original problem is the one linked to the variable m.

\(\displaystyle 6m-4m=2m\)

So then we have 

\(\displaystyle 6p^{3}+4p^{2}+2m-7v\)

Example Question #31 : Adding And Subtracting Polynomials

Subtract the following polynomials:

\(\displaystyle (-2x^2 + 4x - 9) - (-5x^2 - 2x +1)\)

Possible Answers:

\(\displaystyle -7x^4 + 2x^2 - 8\)

\(\displaystyle 3x^4 + 6x^2 - 10\)

\(\displaystyle -7x^2 +2x -8\)

\(\displaystyle 7x^2 -2x +10\)

\(\displaystyle 3x^2 + 6x - 10\)

Correct answer:

\(\displaystyle 3x^2 + 6x - 10\)

Explanation:

When subtracting polynomials, we must first distribute the negative through the second polynomial.

\(\displaystyle (-2x^2 + 4x - 9) {\color{Red} - }(-5x^2 - 2x +1)\)

To do this, we simply take each term in the second polynomial times -1.  We get

\(\displaystyle (-2x^2 + 4x - 9) +5x^2+2x-1\)

We can remove the parentheses from the first polynomial.

\(\displaystyle -2x^2 + 4x - 9 +5x^2+2x-1\)

Now, we combine like terms.  Like terms are the terms that have the same variables.  

\(\displaystyle {\color{Red} -2x^2} {\color{Green} + 4x} {\color{Blue} - 9} {\color{Red} +5x^2}{\color{Green} +2x}{\color{Blue} -1}\)

The like terms have been highlighted.  When we combine them, we get

\(\displaystyle {\color{Red} 3x^2} {\color{Green} + 6x} {\color{Blue} -10}\)

Example Question #1 : Multiplying And Dividing Polynomials

Multiply:
\(\displaystyle -2x(x^4-x^2+4)\)

 

Possible Answers:

\(\displaystyle -2x^5-2x^3+8x\)

\(\displaystyle -2x^5+2x^3-8x\)

\(\displaystyle -2x^3-2x+\frac{2}{x}\)

\(\displaystyle -2x^3+2x-\frac{2}{x}\)

Correct answer:

\(\displaystyle -2x^5+2x^3-8x\)

Explanation:

Multiply making sure to distribute the negative sign:

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

\(\displaystyle =-2x^5+2x^3-8x\)

Example Question #2 : Multiplying And Dividing Polynomials

Multiply: \(\displaystyle (x^2+2)(-x^3+3x-1)\)

Possible Answers:

\(\displaystyle -x^6+3x^3-x^2+6x-2\)

\(\displaystyle -x^5+3x^3-x^2+6x-2\)

\(\displaystyle -x^5+x^3-x^2+6x-2\)

\(\displaystyle -x^6+x^3-x^2+6x-2\)

Correct answer:

\(\displaystyle -x^5+x^3-x^2+6x-2\)

Explanation:

\(\displaystyle (x^2+2)(-x^3+3x-1)=-x^5+3x^3-x^2-2x^3+6x-2\)

\(\displaystyle =-x^5+x^3-x^2+6x-2\)

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