1.) 5x + 7 = 3x + 21
2.) 3x - 2(5 - x) = -3(x - 10) + 3x
3.) 5(x + 1) = 3(2x + 3) + 5
Help?
2007-01-08 08:13:46 · 11 answers · asked by Damion 1 in Science & Mathematics ➔ Mathematics
get everything on one side of the equation, and you'll have 0 on the other side. Then you can solve for x.
To remove something from one side, you add by its opposite.
EG:
5x + 7 = 3x + 21
subract 3x + 21 from both sides
2x - 14 = 0
2 (x-7) = 0
2 = 0 or x-7 = 0
2 cannot equal zero, so x -7 = 0 is the solution
x-7=0
x = 7
There ya go.
2007-01-08 08:17:02 · answer #1 · answered by bequalming 5 · 0⤊ 1⤋
1) 5x + 7 = 3x +21
subtract 3x and 7 from each side
2x = 14
divide by 2
x=7
2) 3x - 2(5-x) = -3(x-10)+3x
multiple everything out
3x - 10 + 2x = -3x + 30 +3x
put all like terms together
5x - 10 = 30
add 10 to each side
5x = 40
divide by 5
x = 8
3) Try to figure out the steps yourself, but here is a summary..
multiply everything out
put all like term together
subtract 5x and 14
x should equal -9.
Good Luck!!!
2007-01-08 16:36:10 · answer #2 · answered by Jean R 2 · 0⤊ 0⤋
Problem 1
5x + 7 = 3x + 21
-3x -3x
_________________
2x + 7 = 21
-7 -7
_________________
2x = 14
14 divided by 2 = 7. X=7
Problem 2
3x - 2(5 - x) = -3(x - 10) + 3x <--you need to distribute
After being Distributed:
3x - 10 + 2x = -3x + 30 + 3x
3x - 10 + 2x = 30 <---3x and -3x cancel out = 0, so you
have 30 left
3x - 10 + 2x = 30
3x + 2x = 5x, so 5x - 10 = 30
Final equation:
5x - 10 = 30
+10 +10
_______________
5x = 40
40 divided by 5 = 8. x=8
Problem 3
5(x+1) = 3(2x+3) + 5 <---distribute
After distribution:
5x + 5 = 6x + 9 + 5 <--- 9+5=14
5x + 5 = 6x +14
____________________
5x + 5 = 6x +14
-5x -5x
____________________
5 = x + 14
-14 -14
_____________
-9 = x
=) I hope you know how to distribute and add the x's, or else it would be a problem.
If you have any more of these problems, give them to me! =) I love doing them. They're so fun
2007-01-08 16:27:17 · answer #3 · answered by craz34jason 5 · 0⤊ 0⤋
1.) 5x + 7 = 3x + 21
5x-3x=21-7
2x=14
x=14/2
x=7
2.)3x-2(5-x)=-3(x-10)+3x
3x-10+2x=-3x+30+3x
5x=30+10
5x=40
x=40/5
x=8
3.) 5(x+1)=3(2x+3)+5
5x+5=6x+9+5
5x=6x+14-5
5x-6x=9
-x=9
x=-9
2007-01-08 16:39:55 · answer #4 · answered by dpolo10 1 · 0⤊ 0⤋
You need to simplify all of these, with the goal of getting the variable by itself on one side of the equation, in order to solve them.
I'll show you how to do that with #1, then you can do the rest...
5x + 7 = 3x + 21
-7 -7
5x = 3x + 14
-3x -3x
2x = 14
/2 /2
x = 14
OK, you do the rest :)
2007-01-08 16:18:09 · answer #5 · answered by Anonymous · 0⤊ 0⤋
1.) 5x + 7 = 3x + 21
first you want to get the x's on the same side of the = sign so subtract 3x. now you have 2x + 7 = 21. your main goal is to get x by itself so now subtract 7 on both sides leaving 2x = 14. now divide both sides by 2 to get x by itself leaving x = 7
now do the same thing for # 2 and 3 good luck!!!!
2007-01-08 16:33:40 · answer #6 · answered by Ashley M 2 · 0⤊ 0⤋
1. x = 7
2. x=10
3. x= -9
2007-01-08 16:19:43 · answer #7 · answered by .::Princess::. 1 · 0⤊ 0⤋
1. x = 7
2. x=10
3. x= -9
2007-01-08 16:19:07 · answer #8 · answered by nixdad96 5 · 0⤊ 0⤋
1. =7
2. =8
3. =-9
2007-01-08 16:27:09 · answer #9 · answered by Anonymous · 0⤊ 0⤋
1.) x=7
2.) x=8
3.) x=-9
2007-01-08 16:20:09 · answer #10 · answered by colo 2 · 0⤊ 0⤋