Mathematics
Grade 7
15 min
Multi-step inequalities with decimals
Multi-step inequalities with decimals
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1
Introduction & Learning Objectives
Learning Objectives
Solve multi-step inequalities involving decimal coefficients and constants.
Accurately apply inverse operations to isolate variables in inequalities with decimals.
Correctly reverse the inequality sign when multiplying or dividing by a negative decimal.
Graph the solution set of multi-step inequalities with decimals on a number line.
Check the validity of their solutions for multi-step inequalities with decimals.
Translate real-world scenarios into multi-step inequalities with decimals and solve them.
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In this lesson, you'll learn how to solve inequalities that require more than one...
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Key Concepts & Vocabulary
TermDefinitionExample
InequalityA mathematical statement that compares two expressions using symbols like < (less than), > (greater than), ≤ (less than or equal to), or ≥ (greater than or equal to).x + 3.5 > 7.2
Solution SetThe set of all values for the variable that make an inequality true. Unlike equations, inequalities often have infinitely many solutions.For x > 2.5, the solution set includes all numbers greater than 2.5 (e.g., 2.6, 3, 10.1).
VariableA symbol, usually a letter, that represents an unknown number or quantity in a mathematical expression or equation/inequality.In the inequality 2.5y - 1.0 ≤ 4.0, 'y' is the variable.
DecimalA number that uses a decimal point to represent a whole number and fractional parts (tenths, hundredths, etc.).Numbers like 0.5,...
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Core Formulas
Addition/Subtraction Property of Inequality
If $a < b$, then $a + c < b + c$ and $a - c < b - c$. This also applies to >, ≤, and ≥.
You can add or subtract the same number (including decimals) to both sides of an inequality without changing the direction of the inequality sign.
Multiplication/Division Property of Inequality (Positive Number)
If $a < b$ and $c > 0$, then $ac < bc$ and $\frac{a}{c} < \frac{b}{c}$. This also applies to >, ≤, and ≥.
You can multiply or divide both sides of an inequality by the same positive number (including decimals) without changing the direction of the inequality sign.
Multiplication/Division Property of Inequality (Negative Number)
If $a < b$ and $c < 0$, then $ac > bc$ and $\frac{a}{c} > \frac{b}...
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Challenging
Solve the inequality: 2.1(x - 3) + 1.5 ≥ 0.6x
A.x ≥ 3.2
B.x ≤ 3.2
C.x ≥ 4.8
D.x ≤ 4.8
Challenging
For what value of 'a' is the solution to the inequality ax - 1.5 > 4.5 exactly x < -10?
A.0.6
B.-0.6
C.6
D.-6
Challenging
A rectangular garden has a length of 8.5 meters. The perimeter of the garden must be no more than 30.2 meters. If 'w' is the width of the garden, which inequality represents the possible width, and what is its solution?
A.2(8.5) + 2w ≤ 30.2; w ≤ 6.6
B.8.5 + w ≤ 30.2; w ≤ 21.7
C.2(8.5) + 2w ≥ 30.2; w ≥ 6.6
D.8.5w ≤ 30.2; w ≤ 3.55
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