Answers

2014-11-11T17:17:25+08:00
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
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