Examine by cross multiplying whether the proportions are correct.

a) [[$ \displaystyle\frac {\sqrt{2}} {4} = \displaystyle\frac {3} {\sqrt{2}} $]]



This is is not a proportion.

b) 5 = 6



This is is not a proportion.

c) [[$ \displaystyle\frac {1} {2} + \displaystyle\frac {2} {1} = \displaystyle\frac {3} {12} $]]



This is is not a proportion.

d) [[$ \displaystyle\frac {1} {x} = \displaystyle\frac {3} {4} $]]



This is is not a proportion.