<h3>
Answer:</h3>
B. 3x +y = 4
<h3>
Step-by-step explanation:</h3>
It is perhaps easiest to simply try the equations to see which one works.
For x=0, there are two different kinds of answers:
... A and C: -y = 4
... B and D: y = 4
Since we know y=4 when x=0 (from the point (0, 4)), we can eliminate choices A and C.
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Using the point (1, 1), you can try choices B and D to see which works:
... B: 3·1 +1 = 4 . . . . true (put 1 where x and y are in the equation)
... D: -3·1 +1 = -2 = 4 . . . . false
The appropriate choice is the equation of B: 3x +y = 4.
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<em>Derive the equation from the given points</em>
There are several ways you can derive the equation. Since you have the y-intercept (the point with x=0), you can use the slope-intercept form to start.
The slope (m) is ...
... m = (change in y)/(change in x) = (4 -1)/(0 -1)
... m = -3
We know the y-intercept (b) is 4, so the slope-intercept form of the equation is ...
... y = mx +b
... y = -3x +4
Adding 3x puts this in standard form:
... 3x +y = 4
