7x+2 = 9 where x = 1 or -1
We need to substitute the vale of x first
let's try the positive one first.
7(1)+2 = 9
7 + 2 = 9
9 = 9 correct
let's try the negative one.
7(-1)+2 = 9
-7 + 2 = 9
-5 = 9 incorrect
Meaning that the positive one is the correct answer.
We can simply look for x without the given values
7x+2 = 9
move 2 to the right and change sign
7x = 9 - 2
Subtract
7x = 7
divide by 7 both sides to remove fractions
7x/7 = 7/7
x = 1
There you go :)
I hope it helps
