2kf(x)>2kg(x)⇔{f(x)>g(x)g(x)≥0
2kf(x)<g(x)⇔⎩⎨⎧g(x)>0f(x)<(g(x))2kf(x)≥0
2kf(x)≤g(x)⇔⎩⎨⎧g(x)≥0f(x)≤(g(x))2kf(x)≥0
2kf(x)>g(x)⇔{g(x)≥0f(x)>(g(x))2k{g(x)<0f(x)≥0
2kf(x)≥g(x)⇔{g(x)≥0f(x)≥(g(x))2k{g(x)<0f(x)≥0
f(x)2kg(x)≥0⇔{g(x)≥0f(x)≥(g(x))2k{g(x)<0f(x)≥0