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Senior one mathematics (-1)+(+2)+(-3)+(+4)+. +(-99)+(+ 100)
Mathematics (-1)+(+2)+(-3)+(+4)+...+(-99)+(+100) Answer: Compared with the standard quality, the listening quality of10 in the sample is-65430 respectively. +5 cancels one -5, and the remaining two +5 can't cancel, so we know that the total weight of 10 tin sample is more than the standard 10g,10/0 =1,so the average mass is 454+/kloc.

Mathematics in Senior One:1-2+3-4+5 …+99-100 Original formula = (1-2)+(3-4)+…+(99-100).

=-( 1+ 1+…+ 1)

=- 1*50

=-50

Math topics for senior one: (-1)+2+(-3)+4+...+(-99)+100 (-1)+2+(-3)+4+...+(-99).

=(2- 1)+(4-3)+...+( 100-99)

= 1+ 1+。 . . + 1

= 1x50

=50

3+(-6)+6+(-9)+9+...+27+(-30)

=3+(6-6)+(9-9)+...+(27-27)-30

=3+0+0+..+0-30

=-27

Mathematical calculation in senior one: (-1)+2+(-3)+4+(-5)+6+(-7) ...+(-99)+100 =? A set of two numbers

(- 1)+2= 1,(-3)+4= 1....(-99)+ 100= 1

A * * * has 50 groups.

The result is 50.

Senior one math problems:1+2+(-3)+(-4)+5+6+(-7)+(-8)+…+97+98+(-99)+(-100) every 4 numbers, each group.

***25 zu

So the original formula =-4×25=- 100.

I wish you happiness.

Find 1×2, 2×3, 3×4, the reciprocal of the first grade mathematics. . . . . . 99× 100, the sum of the reciprocal of the first 99 items is actually very simple. You are still young, remember later, and you will use it frequently in your studies.

Write the general term, 1/n*(n+ 1)

The sum of the first n terms =11* 2+1/2 * 3+1/3 * 4+...1/n * (n+1).

= 1/ 1- 1/2+ 1/2- 1/3+ 1/3- 1/4+........ 1/n- 1/(n+ 1)

= 1- 1/(n+ 1)

Therefore, the sum of the first 99 items is: n=99, and it is substituted into1-1(99+1) =1-kloc-0/00 = 99/100.

The above number is the denominator, and the difference is 1. Similarly, if the difference is 2 or 3 or ..., this method can also be used.

Example: The general term is1/(n-1) * (n+1), so find the sum of the first n terms.

Analysis:1(n-1) * (n+1) =1/2 * [1/(n-1)-1(.

So the sum of the first n terms =1/2 [11/3+1/3-1/5+1/7.

If the difference is 3, multiply it by 1/3 before the dismantled items.

A math problem in grade one:1+1/2+2/3+3/4+...+99/100 =? Change 1/2 to1-1/2, and then split the item.

Math 2, 3, 4, 2 in senior one. The area of this circle is reduced: pai [r 2-(r-2) 2] = (4r-4) pai square centimeter.

3。 Always 5 2 = 25.

Because if the ten digits of a two-digit number are A and the single digit number is 5,

This two-digit number is 10a+5,

The square of this two-digit number is (10a+5) 2.

( 10a+5)2 = 10a 2+ 10a+25。

= 100(a^2+a)+25

So the last two numbers are always 25.

4。 (a+b+c)^2=a^2+b^2+c^2+2ab+2bc+2ac,

This is the complete square formula of the sum of three numbers.

Mathematics 1 2 3 1. Two straight lines are parallel and have equal internal angles. 2. error 3. Not good, DCB (please accept if you are satisfied).