Two calculation problems for the master to come to 35

I seem to know it, it doesn't seem to know me.

Question 2 1 [n*(n+2)]=(1 2)*[1 n-1 (n+2)] All the way inside cancel each other out, and the last four items are left to count.

The first question 1 [n*(n+1)*(n+2)]=(1 2)*[1 n-2 (n+1)+1 (n+2)] is also to bring the last and the rest is simple.

The point of these two questions is to make a transformation.

1/n*(n+1)*(n+2)=1/2(1/(n+2)+1/n+2/(n+1))

So, let the left side of the inequality be a,, 2a=1 1+1 3-2 2+1 2+1 4-2 3+. 1/n+1/（n+2）-2/（n+1）=1+1/2+1/（n+1）+1/（n+2）-2/2-2/（n+1）1/2 -1/（n+1）*（n+2）

a=1 4-1 2*(n+1)(n+2)<1 42) The original formula is a,, then 2a=1 1-1 3+1 2-1 4+1 3-1 5+,,1 9-1 11=1 1+1 2-1 10-1 11=72 55

a=36/55

(1) = (2 3 root number 6-5 root number 3) multiplication root number 6 = 4-15 root number 2

2) = root number 48 divided by root number 12 + 2-2 root number 10 + 5 = root number 3 + 7 - root number 10 = 7 + root number 3 - root number 10

<> please ask the wax liquid to pick the wheel and tell the ants.

<> refer to a troublesome forest calendar under the liquid search Chunjing.

Original = 1+3 2-2x 2 2-8

Dear, please [adopt the answer], your adoption is the motivation for me to answer the question, thank you.

(1) m ice = ice * v ice =

2) m increase = ice * v increase =

1) v aluminium = m aluminium aluminium = 540g (

v empty = v total - v aluminum = 300cm -200cm = 100cm (2) m ball = m aluminum + m water = 540g + 100cm * (1g cm) = 640g

Question 1, 1) the density of ice in kilograms per cubic decimeter, kilograms), the mass of ice in kilograms, 2) the density of water in kilograms per cubic decimeter, 1 2 = 2 (kilograms), the ice increases in mass by 2 kilograms.

Question 2, the density of aluminum grams per cubic centimeter, 540 cubic centimeters), the volume of metallic aluminum is 200 cubic centimeters, 300-200 = 100 (cubic centimeters), the volume of the cavity is 100 cubic centimeters, 1 100 + 540 = 640 (grams), and the water-injected aluminum ball is 640 grams.

Is this a recipe? Is there a formula for the formula? Give me.