Question

Kiran says that a solution to the equation `x-7=3` must also be a solution to the equation `3x-21=9`.

Write a convincing explanation as to why this is true. Explain how these are equivalent equations.

Answer 1

Answer: This is true because everything in the first equation was multiplied equally to get to the second equation. Every part was multiplied by three. The first equation is x-7=3 and the second can be seen as 3(x-7=3). The three will not affect x seeing that the entire equation had the same thing done to it.