2000-1990+1980-1970+... +20-10
(the three dots are what i am not understanding, i didn't know how to put them onto a computer, they are actually more centered not on the bottom of the line)
My book tells me the answer is 1000
I'm just not getting what these dots between the two + signs mean or are telling me to do.. any help??
2007-10-04 11:54:06 · 9 answers · asked by Kitterkat 5 in Science & Mathematics ➔ Mathematics
Thank you smart math people! LOL
2007-10-04 12:07:07 · update #1
That means that the series continues in the same way till you reach +20-10.
2000-1990 = 10
1980 - 1970 = 10
1960-1950 = 10
.
.
.
20 - 10 = 10
There are 2000/20 = 100 pairs of terms
100 * 10 = 1000
The sum is 1000
2007-10-04 12:00:04 · answer #1 · answered by gudspeling 7 · 0⤊ 0⤋
... in math means "and so on. If it's at the end of a sequence or series, it means the pattern continues forever. If it's in the middle of a series (like this one is), it means the pattern continues through to where it picks up on the right.
2000 - 1990 + 1980 - 1970 + ... + 20 - 10 means
2000 - 1990 + 1980 - 1970 + 1960 - 1950 + 1940 - 1930 + 1920 - 1910 + (keep this pattern going until you eventually get to ) + 60 - 50 + 40 - 30 + 20 - 10.
To solve, just group the pluses and minuses together (each group is 10), then figure out how many groups you have. Hope this helps, and good luck!
2007-10-04 12:00:45 · answer #2 · answered by Anonymous · 0⤊ 0⤋
The dots indicate that you should continue the pattern that has been set up. If you look at the problem closely you will see that the numbers descend by 10 each time. The problem would go 2000 - 1990 + 1980 - 1970 +1960 - 1950 + 1940... all the way through 10.
Any time you see those dots it just means to continue following the pattern.
I hope that helps! :)
2007-10-04 12:02:52 · answer #3 · answered by writergirl 3 · 0⤊ 0⤋
Those three dots mean to continue the pattern all the way down to 20-10.
So, it would be:
2000-1990+1980-1970+1960-1950+ and then continue adding and subtracting until you get to +20-10.
2007-10-04 11:59:43 · answer #4 · answered by TW 2 · 0⤊ 0⤋
Notice that 2000 - 1990 = 10, and 1980 - 1970 = 10, etc, so it's just adding up 100 10s, or 1000 in all. The dots are called "ellipsis", which means, "more of the same here, but not enough room to print it all".
2007-10-04 11:58:24 · answer #5 · answered by Scythian1950 7 · 0⤊ 0⤋
the three dots are actually a punction symbol called an 'ellipsis'
it means something like continuing on in this manner
so the problem is really saying:
2000 -1990 +1980 -1970 +(continuing in the manner of adding then subtracting the previous number -10, until you get to) +20 -10
2007-10-04 11:57:58 · answer #6 · answered by David F 5 · 1⤊ 1⤋
if u look carefully you can see theres a pattern starting from 2000, you subtract 10 and take away from the number before.. then you subtract 10 and add it to the number before.. the 3 dots jst indicate this pattern is repeated until it reaches 20
2007-10-04 11:58:35 · answer #7 · answered by Anonymous · 0⤊ 0⤋
They just mean to continue the pattern all the way to the ending as it is shown.
Each subsequent number is decreased by 10 rfom the one before it.
50, 40, 30, 20....
... meaning 10, 0, -10, -20....etc etc
Make sense?
2007-10-04 12:00:34 · answer #8 · answered by Anonymous · 0⤊ 0⤋
the subject depend is mixtures. you prefer to work out what number mixtures of four human beings you will get out of 8. In basic math words, you prefer to discover 8C4. Typing that throughout your medical calculator provide you the respond. right here is the way you do the working. form of achieveable 4-individual communities out of 8 pupils = 8C4 8C4 = (8x7x6x5)/(4x3x2x1) = 1680/24 = 70 mixtures.
2016-10-10 07:57:47 · answer #9 · answered by lasandra 4 · 0⤊ 0⤋