Is substitutions the best method to use when one variable is already known
2 answers:
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So, when we're tasked with things like this, rewriting everything in terms of sine and cosine and combining fractions often trivializes things, so doing just that gives us:
So out expression is 1/cos(x).
Answer:
13
Step-by-step explanation:
First, fill in 3 boxes of the table using the given information (blue numbers on the attached table)
"Of the 32 students that have a cell phone, 19 students do not have a tablet."
The top row of the table is students who have a cell phone. Therefore, place 19 in the box in this row that is in the "no tablet" column.
"Of the 70 students that have a tablet, 57 students do not have a cell phone."
The first column of the table is students who have a tablet. Therefore, place 57 in the box in the 2nd row of this column.
"11 students do not have a cell phone or a tablet."
Find the "no cell phone" row and the "no tablet" column and place 11 in the box that coincides.
We can calculate the blank totals using addition (shown by green numbers on the attached table)
- Total students with no cell phone = 57 + 11 = 68
- Total students with no tablet = 19 + 11 = 30
To calculate the number of students who have a cell phone AND a tablet:
⇒ Total students with a cell phone <em>minus</em> students with a cell phone but no tablet
⇒ 32 - 19 = 13
