1) 3a - 5a = 8a + 4
= -2a = 8a + 4
= +2a (cancel both 2a = 0) = 2a ( subtract 2a to 8a = 6)
= 0 = 6 + 4
= o = 10
= empty set
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2.) 2/3 x – 5 / 6 x – 3 = ½ x – 5
Lcm is 6
(6) 2/3 x – 5 / 6 x (6) – 3 (6) = ½ x (6)– 5(6)
12/3 x – 30/6 x -18/3 = 6/2x – 30/5
4x – 5x -6 = 3x-6
i don't know what the next step is.
2007-12-01 11:17:10 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
1) at the step -2a = 8a + 4 you want to get a's on left and leave 4 on the right. Do this by subracting 8a from both sides to get -2a-8a=4
You made a mistake here. think of the a's as apples. What has happened if you lose 2 apples and then lose 8 more? You have lost 10 apples which you write as -10a. The a does not subtract out. So you get
-10a = 4 and then divide by -10 to get a = 4/-10 = -2/5
2) On step 3, -3(6) = -18 and -5(6)=-30 so you get
4x-5x-18 = 3x-30
Now add or subtract to get x's on left and number on right or
4x-5x-3x = -30+18 and simplify to
-4x = -12 and dividing by -4 gives x = 3
2007-12-01 11:32:32 · answer #1 · answered by baja_tom 4 · 0⤊ 0⤋
No, you've fallen into traps on both.
1) 3a - 5a = 8a + 4
Subtract 8a from both sides
-8a +3a -5a = 0 + 4
-10a = 4
a = -4/10
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2.) 2/3 x – 5 / 6 x – 3 = ½ x – 5
Lcm is 6
(6) 2/3 x – 5/6 x (6) – 3 (6) = ½ x (6) – 5(6)
12/3 x – 30/6 x -18 = 6/2 x – 30
4x – 5x - 18 = 3x - 30
Subtract 3x add 18 both sides.
4x - 5x - 3x = 18 - 30
-4x = -12
x = 3
2007-12-01 11:42:52 · answer #2 · answered by Robert S 7 · 0⤊ 0⤋
For number 1, it is wrong.
1) -2a = 8a + 4
You must subtract the 8a.
-2a-8a=-10a. The 8a cancels out.
-10a = 4
Divide by -10 on each side.
It cancels out the -10 and leaves you with
a = 4 divided by -10.
Use a calculator to figure what that is.
2007-12-01 11:30:40 · answer #3 · answered by nikette. 2 · 0⤊ 0⤋
0 is never = to 10 so obviously you are wrong.
Hint: what happened to the a in 0 = 6+4?
2007-12-01 11:28:06 · answer #4 · answered by walyank 6 · 0⤊ 0⤋