I'd suggest using "elimination by addition and subtraction" here, altho' there are other approaches (such as matrices, substitution, etc.).
Note that if you add the 3rd equation to the second, the x terms cancel out, and you are left with the system
- y + 3z = -2
y + z = -2
-----------------
4z = -4, so z = -1.
Next, multiply the 3rd equation by 2: You'll get -2x + 2y + 2z = -2.
Add this result to the first equation. The 2x terms will cancel, leaving you with the system
2y + 2z = -2
y + z = 4
This would be a good time to subst. -1 for z. We then get:
-2y - 2 = -2. Then y must be 0. y = 0.
Now subst. -1 for z and 0 for y in any of the original equations.
For example, x - (-1) + 3(0) = -2, so x + 1 = -2, or x = -3.
Then a tentative solution is (-3, -1, 0).
It's very important that you ensure that this satisfies all 3 of the originale quations.
It would remain the same (4/5). <span>Sin of the angle is unchanged regardless of the size; it is a ratio related only to the angle, not the size of the triangles.</span>
Answer:
1 1/3 hours
Step-by-step explanation:
Pipe 1 alone:
fills the pool in 2 hours
in 1 hour, it fills 1/2 of the pool
Pipe 2 alone:
fills the pool in 4 hours
in 1 hour, it fills 1/4 of the pool
Pipe 1 and Pipe 2 working together:
fill the pool in x hours
in 1 hour, they fill 1/x of the pool
Working together, in 1 hour the two pipes fill 1/2 + 1/4 of the pool.
Working together, in 1 hour the two pipes fill 1/x of the pool.
Therefore,
1/2 + 1/4 = 1/x
2/4 + 1/4 = 1/x
3/4 = 1/x
x = 4/3
x = 1 1/3
Answer: 1 1/3 hours
