Wang Ma went to the vegetable market to buy pork, and the vendor weighed her 4 jin. Wang Ma suspected that the vendor's scale was not accurate. She added her own 100 g weight into the scale and asked to weigh it again. The result was 4.25 Jin. How many liang of pork should the vendor supply Wang Ma?

Wang Ma went to the vegetable market to buy pork, and the vendor weighed her 4 jin. Wang Ma suspected that the vendor's scale was not accurate. She added her own 100 g weight into the scale and asked to weigh it again. The result was 4.25 Jin. How many liang of pork should the vendor supply Wang Ma?

100g = 0.2kg
4.25-4=0.25
0.2:0.25=4:5=0.8
4 * 0.8 = 3.2 kg
4-3.2 = 0.8 kg
8 Jin = 8 Liang

Find a one variable quadratic equation solution method!
The title is "organize a basketball league match, the competition system is a single round robin form (every two pairs have a match), arrange 15 matches, how many teams are there to participate in?
It's a quadratic equation of one variable

n(n-1)/2 =15
n=6

A detailed solution to the application problem of quadratic equation of one variable
There is a project that team a alone completes 5 days more than team a and team B. if team a and team B cooperate for 4 days, and team B alone completes 3 days, half of the project will be completed. How many days will it take for team a and team B to complete the project?

If it takes X days for Party A and Party B to complete the project together, then it takes (x + 5) days for Party A to complete the project alone
According to the meaning of the title: 4 / x + [1 / X-1 / (x + 5)] × 3 = 1 / 2
It is reduced to: X & # 178; - 3x-70 = 0
﹙x－10﹚﹙x＋7﹙＝0
x1＝10
X2 = - 7
The number of days required for Party A to complete the project alone: x + 5 = 10 + 5 = 15 days,
The number of days required for Party B to complete the project alone: 1 (1 / 10-1 / 15) = 30 days