Without solving the eqution, show that 7 is the solution to -3(x-4)=12-7(x-4)?

Answer 1

Just plug 7 in for x and prove that both sides are equal:

-3(x-4) = 12- 7(x-4)

-3(7-4) = 12- 7(7-4)

-3(3) = 12- 7(3)

-9 = 12- 21

-9 = -9

Answer 2

I see the person before me missed the first four words of the question.

To verify the solution without solving the equation, just plug x=7 into the equation. If both sides turn out to be the same, then x=7 is a solution.

-3(7-4) = 12 - 7(7-4)
-3(3) = 12 - 7(3)
-9 = 12 - 21
-9 = -9

Answer 3

If a number is said to be a solution to an equation, then substituting that number into the equation will result in the equation "working", or being a mathematically correct statement.

For this equation, simply substitute 7 for x.
-3(7-4)=12-7(7-4)
-3(3) =12-7(3)
-9 = 12 - 21
-9 = -9

This procedure is especially useful when you have to solve equations that contain the variable, or unknown, under a square root sign. In these instances, you square both sides to get rid of the square root sign. Any negative terms become positive as a result, and the resulting solutions ALWAYS have to be substituted back into the original equation to verify that it is an acceptable answer.
Good luck with your math!

Answer 4

just plug 7 into it
-3 (7 -4) = -3 * (3) = -9
12 - 7(7-4) = 12 - 7 * 3 =-9
since the left side = the right side
7 is the solution

Answer 5

Simply, put in 7 in place of x on both sides of the equal sign and both sides should arrive at the same answer. If it does, that means that 7 is the solution, If it doesn't, 7 is not the correct solution.

Answer 6

LHS
-3(7 - 4)
- 3 x 3
- 9

RHS
12 - 7 x (3)
12 - 21
- 9

LHS = RHS so 7 is the solution.

Answer 7

7 is the only number there which cannot divide 12

Answer 8

simplify:

-3x + 12 = 12 - 7x + 28

combine like terms:

4x = 28

x = 7

Answer 9

I like Geezah's answer.