Answer:
The solution of |3x-9|≤15 is [-2;8] and the solution |2x-3|≥5 of is (-∞,2] ∪ [8,∞)
Step-by-step explanation:
When solving absolute value inequalities, there are two cases to consider.
Case 1: The expression within the absolute value symbols is positive.
Case 2: The expression within the absolute value symbols is negative.
The solution is the intersection of the solutions of these two cases.
In other words, for any real numbers a and b,
- if |a|> b then a>b or a<-b
- if |a|< b then a<b or a>-b
So, being |3x-9|≤15
Solving: 3x-9 ≤ 15
3x ≤15 + 9
3x ≤24
x ≤24÷3
x≤8
or 3x-9 ≥ -15
3x ≥-15 +9
3x ≥-6
x ≥ (-6)÷3
x ≥ -2
The solution is made up of all the intervals that make the inequality true. Expressing the solution as an interval: [-2;8]
So, being |2x-3|≥5
Solving: 2x-3 ≥ 5
2x ≥ 5 + 3
2x ≥8
x ≥8÷2
x≥8
or 2x-3 ≤ -5
2x ≤-5 +3
2x ≤-2
x ≤ (-2)÷2
x ≤ -2
Expressing the solution as an interval: (-∞,2] ∪ [8,∞)
Answer:
b = 12
Step-by-step explanation:
b/3 + 4 = 8
subtract 4 on both sides
b/3 = 4
multiply 3 with 4
b = 12
Answer: -5/12
Step-by-step explanation: Before multiplying two fractions together by multiplying across their numerators and multiplying across their denominators, you should always try to cross-cancel as your first step.
So in this problem, the 2 and 8 cross-cancel to 1 and 4.
Also, watch out for your signs. In this problem we have a negative times a positive so we know that our answer will be negative.
Now we can multiply across the numerators and across the denominators.
So we have 5 · 1 which is 5 and 4 · 3 which is 12.
So our answer is -5/12.
Be very careful with your signs!
