Blake has some quarters and dimes. He has 20 coins worth a total of $2.90. How many of each type of coin does he have?
2 answers:
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When you see questions of this nature, test the individual inequalities and look out for their intersection.
For
Choose a point in the lower or upper half plane created by the line
The above line is the one which goes through the origin.
Now testing (1,0) yields,
That is,
This statement is true. So we shade the lower half of
For
We test for the origin because, it is not passing through the origin.
This yields
This statement is false so we shade the upper half.
The intersection is the region shaded in B. The top right graph
For
Choose a point in the lower or upper half plane created by the line
The above line is the one which goes through the origin.
Now testing (1,0) yields,
That is,
This statement is true. So we shade the lower half of
For
We test for the origin because, it is not passing through the origin.
This yields
This statement is false so we shade the upper half.
The intersection is the region shaded in B. The top right graph