Solve the equation 3.5x-0.8x = 1.08

（3.5-0.8）=1.08
2.7x=1.08
x=1.08÷2.7
x=0.4

Solving the equation x ^ 4-5x ^ 3 + 8x ^ 2-5x + 1 = 0
x^4－5x^3+8x^2－5x+1=0

x^4－5x^3+8x^2－5x+1
=(x-1)(x^3-4x^2+4x-1)
=(x-1)[(x^3-1)-(4x^2-4x)]
=(x-1)[(x-1)(x^2-3x+1)]=0
The results are: X1 = 1, X2 = 1, X3, X4 = (3 ± √ 5) / 2
The first step is to get the solution of the equation by guessing the root, and then solve it by factorization

7/8x-(3/5x-27)=60

7/8x-(3/5x-27)=60
7/8x-3/5x+27=60
7/8x-3/5x=33
11/40x=33
x=120

Automobile, the most important means of transportation in modern life, is getting closer and closer to our life. The piston area of a single cylinder gasoline engine is 120cm2, the piston moving distance in the power stroke is 30cm, and the average pressure of gas is 5 × 105Pa. The calorific value of gasoline is 4.6 × 107j / kg, and the power consumption is 0.2g each time. The work of gas expansion on the piston is 1 J. If 90% of the gasoline is completely burned in the process of doing work each time, what is the heat released by each gasoline combustion J. Exhaust gas temperature during exhaust Internal energy ．

(1) ∵ P = FS, ∵ the pressure of gas expansion on piston: F = PS = 5 × 105Pa × 120 × 10-4m2 = 6000N, the work of gas expansion on piston: w = FS = 6000N × 0.3m = 1800j; (2) the mass of fully burned gasoline M = 0.2 × 10-3kg × 90% = 0.18 × 10-3kg, the heat released by each gasoline combustion

The principle of displacement calculation by graph multiplication is as follows:
A. The displacement is calculated by superposition method;
B. The displacement is calculated by integral method;
C. The displacement is calculated by virtual work principle;
D. Displacement method

Let x ^ y = y ^ x, find dy / dx|x = 1:

X^y=Y^x
ylnx=xlny
y'lnx+y/x=lny+xy'/y （*）
When x = 1, y = 1 is obtained from x ^ y = y ^ X
So take x = 1, y = 1 into (*) to get y '= 1

How to find the conversion formula between cuft and CBM?
Some people say that the difference between "cuft" and "35.315" is equivalent to "CBM".

Converted to: 22.5 "* 16.5" * 18.1 "/ 1728 = volume
For example: 3.89 CFT = 0.11 CBM

What is the relationship between factorization and integral multiplication?

Inverse operation

Find the tangent plane equation of a point on the sphere x ^ 2 + y ^ 2 + Z ^ 2 = 6, make it pass through the known straight line L: (X-2) / (- 1) = (Y-1) / 1 = (Z-2) / (- 1)

Let the parallel line of the straight line L: (2-x) = (Y-1) = (2-z) = k, and the ball equation is: (2-k) & sup2; + (1 + k) & sup2; + (2-k) & sup2; = 6, which is reduced to: K & sup2; - 2K + 1 = 0, Δ = 0, k = 1; that is to say, the straight line L itself is the tangent of the ball

What's the speed of 80 km / h?

"Mai" is a transliteration of "Mile" in English, not km / h
The "Mile" of vehicle speed refers to: mile / hour
But today's speedometer is km / h.1mi = 1.609km/h
80 m = 128.72 km / h
Supplement:
The cars that entered China in the early days were imported from the United Kingdom, the United States, Germany and other countries, using British units. Now some cars imported from the United States also have British dashboard. Some people don't understand the origin and make a mistake. They call km / h Mai, but the abbreviation of Mai is better than 120 km / h, and everyone can understand it!

Solve the equation 3.5x-0.8x = 1.08