Lesson 5-6
Example 1 Graph an Inequality ()
Graph –x + y 20
Solve 2x + y > 20 Original inequality
2x + y – 2x > 20 – 2x Subtract 2x from each side.
y > –2x + 20 Simplify.
Because Ellen cannot sell a negative number of necklaces or earrings, the domain and
range must be nonnegative numbers. Graph the boundary with a dashed line. If we test
(0, 0), the result is 0 > 20, which is false. Shade the half-plane that does not include the
origin. One solution is (8, 10), or 8 necklaces and 10 pairs of earrings.
Kami’s Profit
14
Earrings Sold
12
10
Pairs of
8
6
4
2
O
2 4 6 8 10 12 14
Number of
Necklaces Sold
Check If we test (8, 10), the result is 10 > 4, which is correct. Because the Ellen cannot sell a
fraction of an item, only points with whole-number coordinates can be solutions.