Step-by-step explanation:
the formula to be used is defined by the "rule".
you know how coordinates (or ordered pairs) work ?
the first number is the x value, the second number is the y value.
to mark a given point you first set your pen at the origin, then go the x value along the horizontal x-axis (if x is positive to the right, if x is negative to the left), and from there you go the y value in parallel of the y-axis (if y is positive up, if y is negative down).
that is how the 2 points were marked :
(1, 3) for x = 1, y = 3
(-1, -3) for x = -1, y = -3
now we use the "rule" to find additional points by either inventing an x-value and calculating the corresponding y-value, or the other way around.
just to verify, the 2 given points follow the rule too :
y = 2x + 1
for (1, 3)
3 = 2×1 + 1 = 2 + 1 = 3 correct
for (-1, -3)
-3 = 2×-1 + 1 = -2 + 1 = -1 wrong ! this point does not follow the rule !
that means that point will not be on the line of the equation !
so, (1, 3) follows already the rule.
now, let's find 3 additional points.
I always start with x = 0 :
y = 2×0 + 1 = 0 + 1 = 1
so, the point is (0, 1)
then for x = -1 we did already the calculation : y = -1.
so, the point is (-1, -1).
and, since we have already a point at y = 3, I often also check now for y = -3 :
-3 = 2x + 1
-4 = 2x
x = -4/2 = -2
so, the point is (-2, -3)
and so, the 4 points following the rule are :
(1, 3)
(0, 1)
(-1, -1)
(-2, -3)
now please mark them as described above.
and then, if your marks are correct, all 4 points will be on a line that you can draw when using a ruler.
remember, (-1, -3) will NOT be on this line.
