Answer:
To find out which expression must be added to 3x - 7 to equal 0, we need to solve the equation:
3x - 7 + a = 0
where "a" is the expression to be added.
To solve for "a", we can isolate "a" on one side of the equation by adding 7 to both sides:
3x - 7 + a + 7 = 0 + 7
Simplifying the left side, we get:
3x + a = 7
Therefore, the expression that must be added to 3x - 7 to equal 0 is:
a = -3x + 7
We can check that this is correct by substituting -3x + 7 for "a" in the original equation:
3x - 7 + (-3x + 7) = 0
Simplifying the left side, we get:
3x - 3x - 7 + 7 = 0
0 = 0
The equation is true, which confirms that the expression -3x + 7 must be added to 3x - 7 to equal 0.
Explanation: