Question

Use the equation to complete an algebraic proof that proves the answer is x = 7/6. Write your proof in your journal and upload your answer. You will be awarded 5 points for the statements and 5 points for the reasons.

2x+65=4x−3

Answer 1

Explanation:

Show that if 3x – 7 = 5, then x = 4.

Here, our given statement is 3x – 7 = 5, and we're asked to prove x = 4.

x=4

Statements Reasons

1. 3x – 7 = 5 Given

2. 3x – 7 + 7 = 5 + 7 Addition of 7 to equation (1)

3. 3x + 0 = 5 + 7 Substitution of –7 + 7 = 0 into (2)

4. 3x = 5 + 7 Substitution of 3x + 0 = 3x into (3)

5. 3x = 12 Substitution of 5 + 7 = 12 into (4)

6. 3x⁄3 = 12⁄3 Dividing equation (5) by 3

7. x = 12⁄3 Substitution of 3x⁄3 = x into (6)

8. x = 4 Substitution of 12⁄3 = 4 into (7)

Is there such a thing as being too descriptive? Yep, and that was it, since over half the proof was devoted to telling the reader how to do arithmetic. We'll typically take numerical computation for granted, and write proofs like this: