Chapter 1: Problem 95
Solve each inequality analytically. Write the solution set in interval notation. Support the answer graphically. $$0.6 x-2(0.5 x+0.2) \leq 0.4-0.3 x$$
Short Answer
Expert verified
The solution is \([-8, \infty)\).
Step by step solution
01
Distribute and Simplify
First, distribute the \(-2\) into the expression \((0.5x + 0.2)\). This results in \(0.6x - 2 \times 0.5x - 2 \times 0.2\). Simplifying this gives \(0.6x - 1.0x - 0.4\). The inequality becomes:\[0.6x - 1.0x - 0.4 \leq 0.4 - 0.3x\] which simplifies further to \[-0.4x - 0.4 \leq 0.4 - 0.3x\].
02
Combine Like Terms
To simplify further, add \(0.3x\) to both sides of the inequality:\[-0.4x + 0.3x - 0.4 \leq 0.4\]This simplifies to \[-0.1x - 0.4 \leq 0.4\].
03
Isolate the Variable
Add \(0.4\) to both sides to isolate the terms with \(x\):\[-0.1x - 0.4 + 0.4 \leq 0.4 + 0.4\]This simplifies to:\[-0.1x \leq 0.8\].
04
Solve for x
Now, divide both sides by \(-0.1\) to solve for \(x\). Remember that when dividing by a negative number, the inequality sign flips:\[x \geq -8\].
05
Express the Solution Set
The solution set in interval notation is:\[[-8, \, \infty)\].
06
Graph the Solution
On a number line, graph by drawing a solid circle at \(-8\) and shading to the right towards positive infinity, indicating all values greater than or equal to \(-8\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Interval Notation
Interval notation is a way of writing subsets of the real number line. It uses brackets and parentheses to describe the range of values that satisfy an inequality.
- Brackets, like \(\left[a, b\right]\), indicate that the endpoints \(a\) and \(b\) are included in the interval. This is known as a closed interval.
- Parentheses, like \(\left(a, b\right)\), mean the endpoints are not included. This is referred to as an open interval.
- For half-open or half-closed intervals, a combination of a bracket and a parenthesis is used, such as \(\left[a, b\right)\) or \(\left(a, b\right]\).
Graphical Solutions
Graphical solutions help visualize the solutions to inequalities on a number line or Cartesian coordinate plane. This approach makes it easier to understand which numbers satisfy the inequality.When dealing with the inequality \(x \geq -8\):
- First, locate \(-8\) on the number line, and draw a solid circle over it. The solid circle indicates that \(-8\) is included in the solution set.
- Next, shade the line to the right of \(-8\) to indicate all numbers greater than \(-8\). This shading represents the idea that there are infinitely many solutions stretching towards positive infinity.
Distributive Property
The distributive property is a fundamental algebraic concept that helps simplify expressions and solve equations or inequalities. It states the following for any numbers \(a, b, \text{and}\, c\):\[a(b + c) = ab + ac\]In the given exercise, the distributive property is applied to the term \(-2(0.5x + 0.2)\) to expand the expression:
- Distribute \(-2\) throughout the terms in the parentheses:
- First, multiply \(-2\) by \(0.5x\), resulting in \(-1.0x\).
- Then, multiply \(-2\) by \(0.2\), resulting in \(-0.4\).
- This process transforms the expression into \(-1.0x - 0.4\).