How to measure milk density with balance, beaker and water How to measure the density of milk with a balance, a small beaker and proper amount of water

How to measure milk density with balance, beaker and water How to measure the density of milk with a balance, a small beaker and proper amount of water

Measure the mass M0 of beaker with balance, fill it with water, measure the mass M1 of water and beaker, pour out water, dry beaker, fill it with milk, measure the total mass m2 of beaker and milk (fill it twice, ensure the volume of water and milk is equal), then vwater = vmmilk = (m1-m0) / P
So the density of milk = (m2-m0) / [(m1-m0) / P]
That is = P (m2-m0) / (m1-m0)
(the unit of the process is not written, otherwise it is difficult to understand. P is the density of water.)

How to calculate the expression s (2S + 3) (s ^ 2 + 4) in MATLAB

>> syms s;
s*(2*s+3)*(s^2+4)
ans =
s*(2*s + 3)*(s^2 + 4)

What is the result of a relational expression

Bool type

There are 3 / 4 tons of coal in the canteen, 2 / 5 of which is used, and how much is left?

1－2/5＝3/5

There are two arithmetic sequences 2, 6, 10 , 190 and 2, 8, 14 The common terms of the two arithmetic sequences form a new sequence from small to large, and the sum of each item of the new sequence is calculated

There are two arithmetic sequences 2, 6, 10 , 190 and 2, 8, 14 The common terms of these two arithmetic sequences form a new sequence from small to large, 2, 14, 26, 38, 50 There are 182 − 212 + 1 = 16, which are also arithmetic sequences. The sum of them is 2 + 1822 × 16 = 1472. The sum of the new series is 1472

The speed ratio of car a and car B is 5:8. The two cars leave from a and B at the same time. The two cars meet at a distance of 12 kilometers from the midpoint. How many kilometers is the distance between the two places?

When they met, car a went all the way
5 ÷ (5 + 8) = 5 / 13
The distance between the two places
12 (1 / 2-5 / 13) = 104 (km)

The inequality X4 + (A-1) x2 + 1 ≥ 0 holds, and the value range of a is obtained
I understand what I said on the Internet. The answer is a ≥ - 1
But set X2 to t
Why can't we do it in the usual way?
If the discriminant ≤ 0, the value of a is
-1≤a≤3
Why can't we use mean inequality!

Just because you use t for it
The range of T1 + T2 ≥ 0 and t1t2 ≥ 0 is not considered

It takes 10 hours for passenger cars and 15 hours for freight cars to complete the whole journey. When the distance between passenger cars and freight cars is 1 / 3, the distance between passenger cars and freight cars is 120 kilometers more than that of freight cars

The distance between a and B is s kilometers
s/10 + s/15
= 3s/30 + 2s/30
= s/6
The meeting time is t hours
t = s / (s/6)
=6 hours
(s/10 - s/15) × (t + 1/3) = 120
(s/10 - s/15) × 19/3 = 120
s/30 × 19/3 = 120
S = 10800 / 19 km

Some problems of plane vector calculation
Given that | a | = 2, | B | = 5, a * b = 3, how to calculate | a + B |, | A-B |
What does | a + B | and | A-B | mean
Verification:
(λa)*b=λ(a*b)=a(λb)

(|a-b |a-b | is the norm of vector sum and the norm of vector difference; and (|a-a-b | is the norm of vector difference and the norm of vector difference; and (|a + B |; (a) A-B | is the norm of vector sum and the norm of vector difference; and (|a + B |; (|a + B |) ^ 2 = 2 = [3 / 3 / 10 = 0 [3 / 10 = 0.3 / 10 = 0.3 / 10 = 0.3, 3, 3 [3 [3 / 10 = 0.3 [3, 3 [3 [3 [3 [3 [3 [3 [3 [3 [3] a] a [a [a] is [[a [a [[[a + B - B |) ^ 2 = | a | ^ 2 + | B | ^ 2-2 | - a | - B | - cos (θ) = 4 + 25-20cos, θ = 29 -

Class a used to have two-thirds of the students in class B. now five students are transferred from class B to class A. then the number of students in class A is equivalent to 7 / 8 of that in class B. how many students are there in class A and class B?

There are x people in class B, according to the meaning of the question
2/3x+5=7/8*(x-5)
The solution is x = 45
So there were 45 people in class B
Class A: 2 / 3 * 45 = 30
There are 30 + 45 = 75 people in the two classes