Identify which of the following function are linear. Write LF it is a linear function and X if it is not

1. f(x)=2x+5
2.f(×)=3
3. f(x)=x2+2
4. f(x)= x+2x4
5. f(x)=x-10
6. ×2+y=3
7.y3-4×=10
8.2x=y=4
9. y=2y-5
10. y=2x(x)+5​