Question

how to know the number of solutions in a linear equation (1 solution, infinite solutions or no solutions)

Answer 1

The first one:

`-40x+40=20x-20`

Solving for x:

`-40x-20x=-40-20=>\text{ -60x=-60, so x=1}`

The second one:

`20x+40=40x+20`
`20x-40x=20-40->\text{ -20x=-20= x=1}`

The third one:

`-20x+40=-20x+20`
`-20x+20x=20-40->\text{ 0=-20}`

This one don´t have

And the last one

`40x+40=40x+20`
`40x-40x=20-40=>\text{ 0=-20}`

It doesn't have solution