The sum of two numbers:
x + y = 108
The difference of the same two numbers:
x - y = 78
We can use substitution to figure out x and y:
x - y = 78 can be changed to x = 78 + y
We can plug this into the first equation:
78 + y + y = 108
78 + 2y = 108
2y = 30
y = 15
Now solve for x using any of the two equations. I'll use the first equation since it's easier:
x + 15 = 108
x = 93
This is the answer in exact form
The <em>correct answer</em> is:
4.
Explanation:
Taking these numbers as groups of three, we have 2, 7, 8; 3, 12, 9.
In the first group, we can see that we first add 5 and then add 1.
The next group seems to start from the next consecutive number. That is, the first group starts with 2, and the next group starts with 3. The next terms in the second group are found by adding 5 to the second term of the first group (12 = 7+5) and then adding 1 to the third term of the first group (9=8+1); this is because we added 5 and added 1 previously.
Following this pattern, the next group of three would start from the next consecutive number up, 4. The next two terms would be 17 (12+5=17) and 10 (9+1=10).
2x² + 3x + 1
2x² + 2x + x + 1
(2x + 1)(x + 1)
