3x + 7 = 5x - 11
2007-10-05 13:09:04 · 8 answers · asked by Lucia I 1 in Science & Mathematics ➔ Mathematics
how do we check if the answer is right
2007-10-05 13:22:31 · update #1
Step 1: Group like terms. Remember to change the sign of term that you move.
3x+7=5x-11
3x-5x=-11-7
-2x=-18
-2x/-2=-18/-2
x=9
Check:
3(9)+7=5(9)-11
27+7=45-11
34=34
2007-10-05 13:18:29 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Always think in terms of getting x on its own :
so :
3x + 7 = 5x - 11
add 11 to both sides : ( you could take 7 from both sides - it will still work)
3x + 7 + 11 = 5x -11 +11 then rewrite this so :
3x + 18 = 5x +0 - now move all the x to one side and numbers to the other by subtracting 3x so
3x - 3x +18 = 5x - 3x
rewriting, (remember 3x-3x is 0 - you dont need to know x here)
18 = 2x divide through by 2
18/2 = 2x/2 which is 9 = x
Now just test it to make sure we are right, substituting 9 for x throughout
3x+ 7 = 5x-11
3(9) +7 = 5(9) - 11
27 + 7 = 45 - 11
34 = 34 CORRECT !
2007-10-05 20:22:42 · answer #2 · answered by paddy_mcginnty 1 · 0⤊ 0⤋
Transpose variables to the right and constants to the left:
3x + 7 = 5x - 11
11 + 7 = 5x - 3x
add and subtract:
18 = 2x
divide both sides by 2
18/2 = 2x/2
9 = x
To check, replace the variables with your answer :
3(9) + 7 = 5(9) -11
27 + 7 = 45 -11
34 = 34
and that is your answer. bow....lol
2007-10-05 20:26:01 · answer #3 · answered by mitzbitz 2 · 0⤊ 0⤋
3x+7=5x-11
i would suggest subtracting 7 from both sides first.
3x+7-7=5x-11-11 or easier term 3x+7=5x-11
-7= -7
3x =5x-18
then subtract 3x with like variables: -3x =-3x
0 =2x-18
move the 2x over. -2x= -18
divide by -2(when a negative is x=9
divided by a negative it equals a
positive so:)
check your answer:short way; -2x=-18
-2(9)=-18
-18=-18
long way:3x+7=5x-11
3(9)+7=5(9)-11
27+7=45-11
34=34
2007-10-05 20:24:43 · answer #4 · answered by Anonymous · 0⤊ 0⤋
3x+7=5x-11 Subtract 3x from both sides
-3x -3x
----------------
7=2x-11 Add 11 to both sides
+11 +11
--------------
18=2x Divide both sides by 2 (to get the x alone)
--- ---
2 2
9=x
So the answer is: x=9
To check it, plug 9 in for x.
2007-10-05 20:19:25 · answer #5 · answered by hwonkangel 2 · 0⤊ 0⤋
ok subtract 3x from both sides to get 7=2x-11
then u add 11 to both sides to get 18=2x
divide both sides by 2 and get 9=x
2007-10-05 20:14:09 · answer #6 · answered by retardedfroggy 1 · 0⤊ 0⤋
- 3x and put it under 5x and then youll get 7=2x-11 then youll add 11 to both sides so youll get 18=2x put 2 under 18 and cross out 2 and youll get x=9
2007-10-05 20:13:52 · answer #7 · answered by Anonymous · 0⤊ 0⤋
7=2x-11
2x=18
x=18/2
x=9
now check: 3(9)+7=5(9)-11
does 27+7=45-11?
2007-10-06 01:10:39 · answer #8 · answered by element_op 3 · 0⤊ 0⤋