Hello Josh,
Please post some of the code that you have been executing or eact phrasings of what you enter into Wolfram Alpha. If you have access to Wolfram Mathematica, I highly suggest that you utilize that in the future.
You can solve your problem in Mathematica, with the following two code sequences.
ContourPlot3D[{2 y^2 + z^2 == 1}, {x, -10, 10}, {y, -10, 10}, {z, -10,
10}]
ContourPlot3D[{x == y}, {x, -10, 10}, {y, -10, 10}, {z, -10, 10}]
