Question

(c) 22n+1 +7 is a multiple of 3 for n > 1.​

Answer 1

Well if so then

`</p><p>3\mid(22n+1+7)\wedge n>1 \\</p><p>3\mid2(11n+4)\wedge n>1 \\</p><p>`

Which is false since
`3\mid2` is false. However we have
`3\mid2x` is true if
`x\mid3` or in this case
`11n+4\mid3`.

So it's true in some cases false.

Hope this helps.