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
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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.
Answer:
what you marked blue is right
Step-by-step explanation:
I think
Answer:
<u>9 mph</u>
Step-by-step explanation:
Calvin's first leg of the trip took 0.5 hr (30 minutes) at 6 mph. That means he travelled (0.5hr x 6 mph =) 3 miles. He travelled 3 miles on the return trip, by definition (same path home). At 18 mph, 3 miles would take (3 miles/18 mph =) 0.1667 hours. That makes a total of 6 miles and (0.5 + 0.1667=) 0.6667 hours.
(6 miles)/(0.6667 hours) = 9 mph is Calvin's average speed for the round trip.
Answer:
2:5
Step-by-step explanation:
