thx
2006-11-14 12:10:20 · 9 answers · asked by chris 2 in Science & Mathematics ➔ Mathematics
10-x= -5
10-x-10= -5-10
-x = -15
-(-x) = -(-15)
x=15
2006-11-14 12:19:03 · answer #1 · answered by ashley 2 · 0⤊ 0⤋
15
2006-11-14 21:43:10 · answer #2 · answered by good2beme1958 1 · 0⤊ 0⤋
the rule is to apply the same function to both sides of the equation. The only caveat is the function must have an inverse. "That which you do you must be able to undo". See it in action
10-x = -5
add negative-10 to both sides. (to undo this step, add positive-10 to both sides)
-10 + 10 - x = -10 - 5
subtraction can be confusing: its not communitive (a-b != b-a), and has so many special rules, it is easier to work with addition of negative numbers instead. Just convert the subtractions into adding negative numbers:
-10 + 10 + (-1)*x = -10 + -5
now do some arithmetic
0 + (-1)*x = -15
since 0 is the additive identity, it and the + sign can disapear
(-1)*x = -15
now multiply both sides by -1. This is a funny function in that it is its own inverse. Not too many functions have that property:
(-1)*(-1)*x = (-1)*(-15)
do some multiplication
1x = 15
and since 1 is the multiplicative identity:
x = 15.
Lets check the original equation:
10 - x = -5
substitute x = 15
10 - 15 = -5
yes.
2006-11-14 20:29:03 · answer #3 · answered by s_lee_odegard 3 · 0⤊ 0⤋
15
2006-11-14 20:13:53 · answer #4 · answered by rokbart 2 · 0⤊ 0⤋
x=15
2006-11-14 20:17:43 · answer #5 · answered by thunder2sys 7 · 0⤊ 0⤋
when 10-x=5 you can also say -x+10=-5, you subtract 10 from both sides, you get -x=-15, you divide by a negative one and recieve the answer x=15
2006-11-14 20:19:49 · answer #6 · answered by Anonymous · 0⤊ 0⤋
15
10-15=-5
2006-11-14 20:20:50 · answer #7 · answered by .Anita. 3 · 0⤊ 0⤋
10-x=-5
subtract 10
-x = -15
x = 15
2006-11-14 20:12:44 · answer #8 · answered by Ambino 4 · 0⤊ 0⤋
10-x=-5
10+5=x
15=x
2006-11-14 20:17:51 · answer #9 · answered by j 2 · 0⤊ 0⤋