Algebra 1 : Equations / Inequalities

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #81 : Systems Of Inequalities

Solve the inequality:  \(\displaystyle 6< x-19\)

Possible Answers:

\(\displaystyle x>-13\)

\(\displaystyle x>-25\)

\(\displaystyle x>25\)

\(\displaystyle x< -25\)

\(\displaystyle x< 25\)

Correct answer:

\(\displaystyle x>25\)

Explanation:

Solve by adding nineteen on both sides.

\(\displaystyle 6+19< x-19+19\)

Simplify both sides.

\(\displaystyle 25< x\)

This is also the same as:  \(\displaystyle x>25\)

The answer is:  \(\displaystyle x>25\)

Example Question #81 : Equations / Inequalities

Solve the inequality: \(\displaystyle z-3\geq 16\)

Possible Answers:

\(\displaystyle z\leq 19\)

\(\displaystyle z< 19\)

\(\displaystyle z\geq13\)

\(\displaystyle z\leq13\)

\(\displaystyle z\geq 19\)

Correct answer:

\(\displaystyle z\geq 19\)

Explanation:

In order to solve this inequality, add three on both sides.

\(\displaystyle z-3+3\geq 16+3\)

Simplify both sides of the inequality.

The answer is: \(\displaystyle z\geq 19\)

Example Question #83 : Systems Of Inequalities

Solve the following inequality:  \(\displaystyle -x-9\leq-6\)

Possible Answers:

\(\displaystyle x\leq -3\)

\(\displaystyle x\leq 15\)

\(\displaystyle x\geq 3\)

\(\displaystyle x\leq 3\)

\(\displaystyle x\geq -3\)

Correct answer:

\(\displaystyle x\geq -3\)

Explanation:

Add six on both sides

\(\displaystyle -x-9+6\leq-6+6\)

Simplify both sides.

\(\displaystyle -x-3\leq0\)

Add \(\displaystyle x\) on both sides.

\(\displaystyle -x-3+x\leq0+x\)

Simplify the left side.  Since we are adding a negative variable, it is not necessary to change the sign.

\(\displaystyle -3\leq x\)

The answer is:  \(\displaystyle x\geq -3\)

Example Question #84 : Systems Of Inequalities

Solve the inequality:  \(\displaystyle -3-3x>-2x\)

Possible Answers:

\(\displaystyle x\geq-3\)

\(\displaystyle x< -3\)

\(\displaystyle x\leq-3\)

\(\displaystyle x>-3\)

\(\displaystyle x< 3\)

Correct answer:

\(\displaystyle x< -3\)

Explanation:

Group the x-variables by adding \(\displaystyle 3x\) on both sides of the equation.

\(\displaystyle -3-3x+3x>-2x+3x\)

Simplify both sides of the equation.

\(\displaystyle -3>x\)

Since we did not divide by a negative number, we do not need to switch the direction of the sign.

The answer is:  \(\displaystyle x< -3\)

Example Question #82 : Equations / Inequalities

Solve the inequality:  \(\displaystyle x-15< 66\)

Possible Answers:

\(\displaystyle x< 51\)

\(\displaystyle x< -81\)

\(\displaystyle x>-81\)

\(\displaystyle x< -51\)

\(\displaystyle x< 81\)

Correct answer:

\(\displaystyle x< 81\)

Explanation:

In order to isolate the x-variable, add 15 on both sides of equation.

\(\displaystyle x-15+15< 66+15\)

Simplify both sides of the inequality.

The answer is:  \(\displaystyle x< 81\)

Example Question #1 : How To Find The Solution To An Inequality With Division

Solve for \(\displaystyle x\):

\(\displaystyle 3x-1>x+7\)

Possible Answers:

\(\displaystyle x< 4\)

\(\displaystyle x>2\)

\(\displaystyle x< 2\)

\(\displaystyle x>4\)

None of the other answers

Correct answer:

\(\displaystyle x>4\)

Explanation:

To solve for \(\displaystyle x\), separate the integers and \(\displaystyle x\)'s by adding 1 and subtracting \(\displaystyle x\) from both sides to get \(\displaystyle 2x>8\). Then, divide both sides by 2 to get \(\displaystyle x>4\). Since you didn't divide by a negative number, the sign does not need to be reversed.

Example Question #2 : How To Find The Solution To An Inequality With Division

Solve the following:   \(\displaystyle -2x+3>4\)

Possible Answers:

\(\displaystyle x< -\frac{7}{2}\)

\(\displaystyle x>-\frac{1}{2}\)

\(\displaystyle x< -\frac{1}{2}\)

\(\displaystyle x>-\frac{7}{2}\)

Correct answer:

\(\displaystyle x< -\frac{1}{2}\)

Explanation:

\(\displaystyle -2x+3-3>4-3\)

\(\displaystyle -2x>1\)

\(\displaystyle \frac{-2x}{-2}< \frac{1}{-2}\)    Don't forget to change the direction of the inequality sign when dividing by a negative number!

\(\displaystyle x< -\frac{1}{2}\)

Example Question #3 : How To Find The Solution To An Inequality With Division

Give the solution set of the inequality:

\(\displaystyle -4x + 17 > 81\)

Possible Answers:

\(\displaystyle (-\infty ,16)\)

\(\displaystyle (-\infty ,-16)\)

\(\displaystyle (-16,16)\)

The set of all real numbers

\(\displaystyle \left (-16, \infty \right )\)

Correct answer:

\(\displaystyle (-\infty ,-16)\)

Explanation:

\(\displaystyle -4x + 17 > 81\)

\(\displaystyle -4x + 17 -17 > 81 -17\)

\(\displaystyle -4x > 64\)

\(\displaystyle -4x \div (-4)< 64 \div (-4)\)

Note change in direction of the inequality symbol when the expressions are divided by a negative number.

\(\displaystyle x < -16\)

or, in interval form,

\(\displaystyle (-\infty ,-16)\)

 

Example Question #4 : How To Find The Solution To An Inequality With Division

Give the solution set of the inequality:

\(\displaystyle -5x + 17 \geq 82\)

Possible Answers:

\(\displaystyle [-13,\infty)\)

\(\displaystyle \left [13, \infty \right )\)

\(\displaystyle (-\infty , -13]\)

The inequality has no solution.

\(\displaystyle (-13,13)\)

Correct answer:

\(\displaystyle (-\infty , -13]\)

Explanation:

\(\displaystyle -5x + 17 \geq 82\)

\(\displaystyle -5x + 17 -17 \geq 82-17\)

\(\displaystyle -5x \geq 65\)

\(\displaystyle -5x \div (-5) \leq 65\div (-5)\) 

Note change in direction of the inequality symbol when the expressions are divided by a negative number.

\(\displaystyle x \leq -13\) 

or, in interval form,

\(\displaystyle (-\infty , -13]\)

Example Question #83 : Equations / Inequalities

Give the solution set of the inequality:

\(\displaystyle -5x + 27 \leq 62\)

Possible Answers:

\(\displaystyle [7,\infty )\)

The inequality has no solution.

\(\displaystyle [-7,\infty )\)

\(\displaystyle [-7,7]\)

\(\displaystyle (-\infty , -7]\)

Correct answer:

\(\displaystyle [-7,\infty )\)

Explanation:

\(\displaystyle -5x + 27 \leq 62\)

\(\displaystyle -5x + 27 -27 \leq 62-27\)

\(\displaystyle -5x \leq 35\)

\(\displaystyle -5x \div (-5) \leq 35\div (-5)\) 

Note change in direction of the inequality symbol when the expressions are divided by a negative number.

\(\displaystyle x \geq -7\) 

or, in interval form,

\(\displaystyle [-7,\infty )\)

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