Using interval notation to express all real numbers less than or equal to
a Or greater than or equal to
b
Write the interval expressing all real numbers less than or equal to
or greater than or equal to
We have to write two intervals for this example. The first interval must indicate all real numbers less than or equal to 1. So, this interval begins at
and ends at
which is written as
The second interval must show all real numbers greater than or equal to
which is written as
However, we want to combine these two sets. We accomplish this by inserting the union symbol,
between the two intervals.
When we work with inequalities, we can usually treat them similarly to but not exactly as we treat equalities. We can use the
addition property and the
multiplication property to help us solve them. The one exception is when we multiply or divide by a negative number; doing so reverses the inequality symbol.
Properties of inequalities
These properties also apply to
and
Demonstrating the addition property
Illustrate the addition property for inequalities by solving each of the following:
(a)
(b)
(c)
The addition property for inequalities states that if an inequality exists, adding or subtracting the same number on both sides does not change the inequality.
Solving inequalities in one variable algebraically
As the examples have shown, we can perform the same operations on both sides of an inequality, just as we do with equations; we combine like terms and perform operations. To solve, we isolate the variable.
Solving an inequality algebraically
Solve the inequality:
Solving this inequality is similar to solving an equation up until the last step.
The solution set is given by the interval
or all real numbers less than and including 1.
t he silly nut company makes two mixtures of nuts: mixture a and mixture b. a pound of mixture a contains 12 oz of peanuts, 3 oz of almonds and 1 oz of cashews and sells for $4. a pound of mixture b contains 12 oz of peanuts, 2 oz of almonds and 2 oz of cashews and sells for $5. the company has 1080
Lairene and Mae are joking that their combined ages equal Sam’s age. If Lairene is twice Mae’s age and Sam is 69 yrs old, what are Lairene’s and Mae’s ages?
