Which expression is prime? A) x2 - 9 B) 1 - 9x2 C) 2a2 - 25 D) 4x2 - 9
1 answer:
You might be interested in
Answer:
66
Step-by-step explanation:
If there are <em>n</em> students, then the number of pairs is .
With 12 students, pairs can be formed.
The reason the formula works is this: Each of the 12 students can be paired with 11 other students (no student is paired with him/her self). But counting 12 x 11 = 132 counts each pair <u>twice</u>. Example: student A can be paired with student B,..., student B can be paired with student A. The pair was counted two times.
See the attached image that shows pairings of 5 students. There are
5(5 - 1)/2 = 5(4)/2 = 10 pairs.
Answer:
Only area of PQR can be calculated.
Step-by-step explanation:
In PQR, we have both the base (24 cm) and the height (15cm) which is perpendicular to the base. Therefore using these two measurements, we can take
This is equal to 180 cm².