Solve the equation. 5t^3 +40t^2 = -80t
1 answer:
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Answer:
(x, y) = (-1, 4), (2, -1), (5, -6)
Step-by-step explanation:
You can choose any value you like for either x or y, then solve for the other value. I like to plot points with integer coefficients, so I would look for sets of those.
The nature of this equation is that it will have integer solutions with x-values spaced 3 apart and y-values spaced 5 apart. (The spacing of each corresponds to the coefficient of the other.) So, the trick is to find an x-value that gives an integer solution for y. (You will need to try at most 3 consecutive integers.)
Solving the equation for y, we get ...
y = -5/3x +7/3
Right away, we know that x=0 will not give an integer solution for y. Nor does x=1. The third consecutive integer that is easy to try is x = -1, so ...
y = (-5/3)(-1) +7/3 = (5+7)/3 = 4 . . . . an integer value for y
Our first point is then (x, y) = (-1, 4).
Since the slope is negative, we know that increasing x will decrease y. Thus we can simply add (3, -5) to any point to get another point on the line.
Two more points on the line are ...
(-1, 4) +(3, -5) = (2, -1)
(2, -1) +(3, -5) = (5, -6)
Three integer-valued points on this line are (-1, 4), (2, -1), (5, -6).
