Question

Are these functions linear or nonlinear

y = −10.2

3x + 5y = 15

Answer 1

Both are linear.

Linear function equation : y=mx+c

You can show the first equation like this =
`y=0\cdot x+(-10.2)`

As you can see it is a linear function. Only, x's coefficent is 0.

The second one :
`3x+5y=15\\ \\ 5y=15-3x\\ \\ y=\frac { 15-3x }{ 5 } =\quad y=\frac { -3x+15 }{ 5 }`

As you can see it is also a linear function.