Answer:
A. {x,y}={-2,-3}
// Solve equation [2] for the variable x
[2] x = 2y + 4
// Plug this in for variable x in equation [1]
[1] (2y+4) - y = 1
[1] y = -3
// Solve equation [1] for the variable y
[1] y = - 3
// By now we know this much :
x = 2y+4
y = -3
// Use the y value to solve for x
x = 2(-3)+4 = -2
B. [1] 3x=3y-6
[2] y=x+2
Equations Simplified or Rearranged :
[1] 3x - 3y = -6
[2] -x + y = 2
Solve by Substitution :
// Solve equation [2] for the variable y
[2] y = x + 2
// Plug this in for variable y in equation [1]
[1] 3x - 3•(x +2) = -6
[1] 0 = 0 => Infinitely many solutions
C.Step by Step Solution
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System of Linear Equations entered :
[1] 4x - y = 2
[2] 8x - 2y = 4
Solve by Substitution :
// Solve equation [1] for the variable y
[1] y = 4x - 2
// Plug this in for variable y in equation [2]
[2] 8x - 2•(4x-2) = 4
[2] 0 = 0 => Infinitely many solutions
Without the actually predicted values in comparison to the real values it is only possible to give a very likely answer based on their scale:
a) is 25 million off, which sounds bad but when compared to a few billion in population it's not even 1%
b)3 billion is more than half the world population as error: very unlikely
c)154 billion, unlikely that a prediction is off by a factor of ~30
d)same as c
so a) is most likely the solution, but in theory the predictions could be arbitrarily bad (things like negative population, or extreme growths)
<span>Simplifying
3(5 + -1e) + 2 = 10
(5 * 3 + -1e * 3) + 2 = 10
(15 + -3e) + 2 = 10
Reorder the terms:
15 + 2 + -3e = 10
Combine like terms: 15 + 2 = 17
17 + -3e = 10
Solving
17 + -3e = 10
Solving for variable 'e'.
Move all terms containing e to the left, all other terms to the right.
Add '-17' to each side of the equation.
17 + -17 + -3e = 10 + -17
Combine like terms: 17 + -17 = 0
0 + -3e = 10 + -17
-3e = 10 + -17
Combine like terms: 10 + -17 = -7
-3e = -7
Divide each side by '-3'.
e = 2.333333333
Simplifying
e = 2.333333333</span>