Hi, my daughter is doing her homework and unfortunately I suck at math, please help....
the equation is:
5x+7 = 3x -5
How do I solve this math equation??
2008-03-12 5:04 am
回答 (12)
2008-03-12 5:08 am
✔ 最佳答案
5x+7 = 3x -5subtract 3x from both sides.
2x + 7 = -5
subtract 7 from both sides.
2x = -12
divide by two to both sides.
x = -6
2008-03-12 5:53 am
5x + 7 = 3x - 5
5x - 3x + 7 = 3x - 3x - 5 (Subtract 3x from both sides)
-> 2x + 7 = -5
2x + 7 - 7 = -5 - 7 (Subtract 7 from both sides)
-> 2x = -12
2x/2 = -12/2 (Divide both sides by 2 to isolate x)
-> x = -6
The answer is x = -6
5x - 3x + 7 = 3x - 3x - 5 (Subtract 3x from both sides)
-> 2x + 7 = -5
2x + 7 - 7 = -5 - 7 (Subtract 7 from both sides)
-> 2x = -12
2x/2 = -12/2 (Divide both sides by 2 to isolate x)
-> x = -6
The answer is x = -6
2008-03-12 5:08 am
Add the same thing to both sides of the equation so that the variables end up on one side and the constants end up with the other.
Then the cooefficient on the variable gets divided both sides to leave the variable by itself:
5x + 7 = 3x - 5
Add -3x - 7 to both sides:
2x = -12
divide 2 to both sides.
x = -6
Then the cooefficient on the variable gets divided both sides to leave the variable by itself:
5x + 7 = 3x - 5
Add -3x - 7 to both sides:
2x = -12
divide 2 to both sides.
x = -6
2008-03-12 5:07 am
5x+7 = 3x -5
-3x .....-3x
2x + 7 = -5
.......-7....-7
2x = -12
/2....../2
x = -6
To check, plug in -6 for each of the x's.
5(-6) + 7 = 3(-6) -5 <<--- We hope they are equal.
-30 +7 = -18 - 5
-23 = -23 <<--- They are equal, so x = -6 is correct.
I hope this helps!
-3x .....-3x
2x + 7 = -5
.......-7....-7
2x = -12
/2....../2
x = -6
To check, plug in -6 for each of the x's.
5(-6) + 7 = 3(-6) -5 <<--- We hope they are equal.
-30 +7 = -18 - 5
-23 = -23 <<--- They are equal, so x = -6 is correct.
I hope this helps!
2016-05-28 8:12 pm
t=3
2008-03-12 10:12 am
5x + 7 = 3x - 5
5x - 3x = -7 - 5
2x = -12
x = -12/2
x = -6
5x - 3x = -7 - 5
2x = -12
x = -12/2
x = -6
2008-03-12 5:13 am
5x+7=3x-5
5x - 3x = -5 -7
2x = -12
x = -6
5x - 3x = -5 -7
2x = -12
x = -6
2008-03-12 5:12 am
5x-3x = -7-5
2x = -12
x = -12/2
x = -6
2x = -12
x = -12/2
x = -6
2008-03-12 5:11 am
5x+7=3x-5
2x+7=-5
2x=-12 <(second and third lines) put common variables on the same side (the x's with x's whole #'s with whole #'s
then you divide by 2 to get x isolated
x=-6 (divide by -1 to get a positive answer)
2x+7=-5
2x=-12 <(second and third lines) put common variables on the same side (the x's with x's whole #'s with whole #'s
then you divide by 2 to get x isolated
x=-6 (divide by -1 to get a positive answer)
2008-03-12 5:09 am
isolate the x value: 7 +5 = 3x - 5x
combine like terms. 12= -2x
divide to solve 12 / -2 = -2x/-2
so, -6 = x
combine like terms. 12= -2x
divide to solve 12 / -2 = -2x/-2
so, -6 = x
參考: =] QED
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