1.) 5x + 7 = 3x + 21
2.) 3x - 2(5 - x) = -3(x - 10) + 3x
3.) 5(x + 1) = 3(2x + 3) + 5
2007-08-16 17:43:00 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Question 1
2x = 14
x = 7
Question 2
3x - 10 + 2x = - 3x + 30 + 3x
5x - 10 = 30
5x = 40
x = 8
Question 3
5x + 5 = 6x + 9 + 5
5x = 6x + 9
x = - 9
2007-08-16 22:12:50 · answer #1 · answered by Como 7 · 2⤊ 0⤋
The general thing to remember while solving the equations is to move all the variables in LHS and constants in RHS.
1.) 5x + 7 = 3x + 21
5x - 3x = 21 - 7
2x = 14
divide both sides by 2
2x / 2 = 14 / 2
x = 7
2.) 3x - 2(5 - x) = -3(x - 10) + 3x
first open the parenthesis
3x - 10 + 2x = -3x + 30 + 3x
5x - 10 = 30
rearrange the equation
5x = 30 + 10
5x = 40
divide both sides by 5
5x / 5 = 40 / 5
x = 8
3.) 5(x + 1) = 3(2x + 3) + 5
first open the parenthesis
5x + 5 = 6x + 9 + 5
5x + 5 = 6x + 14
rearrange the equation
5x - 6x = 14 - 5
-x = 9
multiply both sides by -1
x = -9
2007-08-17 02:35:53 · answer #2 · answered by Sam 3 · 0⤊ 0⤋
1.) 5x + 7 = 3x + 21
5x - 3x = 21 - 7
2x = 14
2x / 2 = 14 / 2
x = 7
2.) 3x - 2 (5 - x) = -3(x-10) + 3x
3x - 10 + 2x = -3x + 30 + 3x
5x = 40
5x/5 = 40/5
x = 8
3.) 5(x + 1) = 3 (2x + 3) + 5
5x + 5 = 6x + 14
5x - 6x = 14 - 5
-x = 9
x = -9
2007-08-17 02:37:06 · answer #3 · answered by ChAoScI 1 · 0⤊ 0⤋
1) 5x + 7 = 3x + 21
2x = 14
x = 7
2) 3x -2(5 - x) = -3(x - 10) + 3x
3x - 10 + 2x = -3+ 30 + 3x
2x = 37
x = 18.5
3) 5(x+1) = 3(2x + 3) + 5
5x + 5 = 6x + 9 +5
-x = 9
x = -9
2007-08-17 00:54:44 · answer #4 · answered by n00b_pwn 1 · 0⤊ 0⤋
1) 5x + 7 = 3x + 21
2x = 14
x = 7
2) 3x - 2(5 - x) = -3(x - 10) + 3x
3x - 10 + 2x = -3x + 30 + 3x
5x - 10 = 30
5x = 40
x = 8
3) 5(x + 1) = 3(2x + 3) + 5
5x + 5 = 6x + 9 + 5
-x = 9
x = -9
2007-08-17 08:31:47 · answer #5 · answered by 痴心情长剑 3 · 0⤊ 2⤋
1.) 5x + 7 = 3x + 21
5x - 3x = 21 - 7
2x = 14
x = 14 / 2
Answer: x = 7
Proof:
5(7) + 7 = 3(7) + 21
35 + 7 = 21 + 21
42 = 42
2.) 3x - 2(5 - x) = - 3(x - 10) + 3x
3x - 10 + 2x = - 3x + 30 + 3x
5x = 30 + 10
5x = 40
x = 40 / 5
Answer: x = 8
Proof:
3(8) - 2(5 - 8) = - 3(8 - 10) + 3(8)
24 - 2(- 3) = - 3(-2) + 24
24 + 6 = 6 + 24
30 = 30
3.) 5(x + 1) = 3(2x + 3) + 5
5x + 5 = 6x + 9 + 5
5x - 6x = 9 - 5 + 5
- x = 9
Answer: x = - 9
Proof:
5(- 9 + 1) = 3(2[- 9] + 3) + 5
5(- 8) = 3(- 18 + 3) + 5
- 40 = 3(- 15) + 5
- 40 = - 45 + 5
- 40 = - 40
2007-08-17 00:58:41 · answer #6 · answered by Jun Agruda 7 · 3⤊ 1⤋
Okay!
Enjoy, http://youtube.com/watch?v=DTg6SK1BHRw
1)5x + 7 = 3x + 21
2x=14
x=7
2)3x - 2(5 - x) = -3(x - 10) + 3x
3x-10+2x=-3x+30+3x
5x-10=30
5x=40
x=8
3)5(x + 1) = 3(2x + 3) + 5
5x+5=6x+9+5
-x=9
x=-9
2007-08-17 00:50:09 · answer #7 · answered by Anonymous · 0⤊ 0⤋
1.) x=7
2.)x=8
3.)x=-9
2007-08-17 00:52:06 · answer #8 · answered by Yankees Bryce 2 · 0⤊ 0⤋