Given:
x+7y=8 ...(1)
x=4-7y ...(2)
Rearrange (2) to give
x+7y=8 ...(1a)
x+7y=4 ...(2a)
Since the left-hand sides are identical, but the right-hand sides are different, we conclude that the system of equation is inconsistent and hence has no solution.
solve
x+7y=8
x=4-7y
1 answer