2x+3y+4z = 12
3x+y+z = 4
x+4y+z = 5
The solution to that is x=11/32, y=9/16, z=77/32
Those are bad fractions, so it's likely that you made
a mistake in copying the problem. Doing a system by
Gaussian elimination is very tedious when the answers
aren't simple. Check to make sure you copied it right,
and didn't miss a sign or type a number wrong. If you
did, you can tell me in the thank you note form below
and I'll get back to you by email and explain how.
2. By using RegulaFalsi method find the root of 15 correct
up to 2 decimal places.
The square root of 16 is 4.
So we guess a little less than 4.
So we guess 3.8
3.8² = 14.44 too small
Try 3.9
3.9² = 15.21 too large
Try something between 3.8 and 3.9.
Since 15.21 is closer to 15 than 14.44, we
try something closer to 3.9, say 3.87.
3.87² = 14.9769 too small
So it's between 3.87 and 3.9
Since 14.9769 is closer to 15 than 15.21, we
try something closer to 3.87, say 3.872.
3.872² = 14.9923384 too small
Getting close though!
So it's between 3.872 and 3.9
Since 14.9923384 is closer to 15 than 15.21, we
again try something closer to 3.872, say 3.873.
3.873² = 15.000129 too large.
Since 3.872 is too small and 3.873 is too large and
both round off to 3.87, we can stop here.
Answer to 2 decimal places: 3.87
Edwin