Which equation is a linear function?

Step-by-step explanation:

In general ,A linear function has the form y = ax + b

so ,the functions :

y = √x

y = x²

y = x³

don’t meet the requirements of the definition

therefore none of them is linear.

but y = x is a valid choice (just put a = 1 and b = 0  in the expression y = ax + b)

option 3 . (5x + 1) - (-10x + 6)

step-by-step explanation:

option 1 :

(4x + 3) + (-9x + 4)

or 4x+3 -9x + 4

or -5x + 7

option 2

(x - 2) - (6x - 9)

or x-2-6x + 9

or -5x + 7

option 3

(5x+ + 6)

or 5x + 1 + 10x -6

or 15x -5

option 4

-4x+2x+7-3x

-7x + 2x + 7

-5x + 7

hence only option 3 did   not satisfy the given simplify expression.