can someone please help me find a number for a that CAN NOT BE USED -1 + 5 x- 9 ( - 2 + 5 x ) = a x + b

I have no idea what your question means.

Arithmetic operations give the result:

- 1 + 5 x - 9 ( - 2 + 5 x ) = a x + b

- 1 + 5 x - 9 ∙ ( - 2 ) - 9 ∙ 5 x = a x + b

- 1 + 5 x + 18 - 45 x = a x + b

- 40 x + 17 = a x + b

a = - 40 , b = 17

so, any a ≠ -40 does not satisfy the equation

To find the value for 'a', we need to solve the given equation:

-1 + 5x - 9(-2 + 5x) = ax + b

Let's simplify the equation step by step:

First, distribute the -9 to the terms inside the parentheses:

-1 + 5x + 18 - 45x = ax + b

Combine like terms:

(-1 + 18) + (5x - 45x) = ax + b

17 - 40x = ax + b

Now, we can see that the equation is in the form of "constant + variable = constant + variable". To solve for 'a', we need an equation in the form of "variable = constant + variable".

Rearrange the equation by moving all terms with 'a' to one side:

-40x - ax = b - 17

Factor out 'a' from the terms with 'a':

(-40 - x)a = b - 17

Finally, divide both sides of the equation by (-40 - x) to solve for 'a':

a = (b - 17) / (-40 - x)

Now, keep in mind that you mentioned finding a number for 'a' that cannot be used. We need more information to identify any specific constraints or conditions for 'a'.