Who can I solve this simple equation It is proved that the value of the algebraic formula 3x Λ 2-6x + 5 is not less than 2 Thank you for your help

Who can I solve this simple equation It is proved that the value of the algebraic formula 3x Λ 2-6x + 5 is not less than 2 Thank you for your help

3X^2-6X+5
=3(X^2-2X)+5
=3(X-1)^2-3+5
=3(X-1)^2+2
Constant not less than 2

Simple equation problem, with equation solution
Xiao Jie went to the post office to buy 20 envelopes of two types. It cost 12 yuan to buy the envelope of model a and 15 yuan to buy the envelope of model B. each envelope of model a is 0.3 yuan cheaper than that of model B. how much is the unit price of these two types of envelopes

Suppose that the envelope of model a is x yuan each, and that of model B is (x + 0.3) yuan each
12/x+15/(x+0.3)=20
Multiply x (x + 0.3) to get:
12(x+0.3)+15x=20x(x+0.3)
20x^2-21x-3.6=0
The solution is X1 = 1.2, X2 = - 3 / 20 (rounding off negative value)
Answer: each envelope of model a is 1.2 yuan, and each envelope of model B is 1.5 yuan

(3x-2）²=1
x(x+8)=16
x²+4x-1=0
X-radical 2 = 5x (radical 2-x)

1.
(3x-2)²-1=0
(3x-2+1)(3x-2-1)=0
x1=1,x2=3
two
x²+8x-16=0
(x+4)²-32=0
X1 = - 4-4 radical 2, X2 = - 4 + 4 radical 2
three
x²+4x+4-5=0
(x+2)²-5=0
X1 = - 2-radical 5, X2 = - 2 + radical 5
four
X-radical 2-5x (radical 2-x) = 0
(x-radical 2) (1 + 5x) = 0
X1 = radical 2, X2 = - 0.2

1/X²-10x-29 +1/X²-10x-35 +1/X²-10x-69=0

Let X & # 178; - 10x-29 = y, then x & # 178; - 10x-35 = y-6, X & # 178; - 10x-69 = y-40
1/y＋1/(y－6)＋1/(y－40)＝0
Find y and then X

Xiaoming and Xiaohong play games. Xiaoming takes out a calendar: "I circled a 2 × 2 square with a pen, and the sum of their numbers is 76. Do you know which numbers I circled?" can you help Xiaohong solve it?

x+（x+7）+（x+1）+（x+8）=4x+16
4x+16=76
4x=60
x=15
15+7=22,15+1=16,15+8=23
A: these four numbers are 15, 22, 16 and 23

(1-x) / 3-2x = 3 - (x + 2) / 4 find x

Multiply both sides by 12 to get 4-28x = 30-3x and finally x = - 26 / 25

Li Wei rides a motorcycle from home to the railway station. If he travels 30 kilometers per hour, he will be 15 minutes earlier than the train. If he travels 18 kilometers per hour, he will be 15 minutes later than the train's departure time. If Li Wei plans to arrive at the railway station 10 minutes before the train leaves, what's the speed of his motorcycle at this time?

Let the departure time of the train be x hours. From the meaning of the question: 30 (x-1560) = 18 (x + 1560), the solution is x = 1. Let Li Wei's cycling speed be y kilometers per hour, y = 30 × (1 − 1560) 1 − 1060 = 27. Therefore, Li Wei's cycling speed is 27 kilometers per hour

2. The price of a certain teapot sold in the store is 20 yuan per teacup and 3 yuan per teacup. The store held a special promotion in the marketing season, that is, to buy a teapot and give away a teacup. A customer spent 170 yuan to buy back 38 teapots and teacups. How many teapots and teacups did the customer buy back?

If you buy x teapots, you will get x free cups and Y free cups
20*X+3*Y=170
X + X + y = 38, x = 4, y = 30

If a car drives from a to B according to the original plan, it will arrive on time if it drives 40 km / h in the first half of the time, and 60 km / h in the second half of the time. However, the car fails when it drives from a to a place 40 km away from the midpoint of AB at the speed of 50 km / h, stops for 1 hour, and then continues to drive to B at the speed of 60 km / h, The result is still on time. Ask the distance of AB and the time needed to drive as planned

Let the time of the original plan be x (H) and the distance of AB be y (km)
0.5x×40+0.5x×60=y ①
[(0.5y-40)÷50]+1+[(0.5y+40)÷60]=x②
From 1
y=50x ③
Substitute (3) for (2)
Then it can be solved
x=9.2
y=460
A: the AB distance is 460km, and the original planned time is 9.2h

① Xiao Ming is 6 years old and his father is 72 years old. A few years later, Xiao Ming will be a quarter of his father's age?
② My father saved a 6-year education savings for Xiao Ming. The 6-year annual interest rate is 2.7%. After 6 years, he can withdraw 5810 yuan. How many yuan does he begin to deposit?
③ In order to save energy, a unit will charge a monthly electricity charge according to the following regulations. If the electricity consumption is not more than 140 kwh, the charge will be 0.43 yuan per kWh. If the electricity consumption is more than 140 kwh, the charge will be 0.57 yuan per kWh. If the average electricity charge of a user is 0.5 yuan per kwh in April, how much should the user pay in April?
④ The distance between a and B is 300 kilometers. A local train starts from a and runs 60 kilometers per hour
An express train starts from B and runs 90 kilometers per hour
(1) The two cars left at the same time, and they went opposite each other. How many hours after they started, did they meet?
(2) If the local train is ahead, how many hours after departure can the express catch up with the local train?
Give me the above formula (must be equation) and the answer