Math problem X-1 / x = 3 x & # 178; + 1 / X & # 178; =? x-1/x=3 x²+1/x²=? Why does x + 1 / x = 3 x & # 178; + 1 / X & # 178; = 7 not understand (x + 1 / x) &# 178; should get 9

Math problem X-1 / x = 3 x & # 178; + 1 / X & # 178; =? x-1/x=3 x²+1/x²=? Why does x + 1 / x = 3 x & # 178; + 1 / X & # 178; = 7 not understand (x + 1 / x) &# 178; should get 9

1.X－1／X=3﹙X－1／X﹚²＝9X²－2 × X ×﹙1／X﹚﹢﹙1／X﹚²=9X²－2 ﹢﹙1／X﹚²=9X²﹢﹙1／X﹚²=112.X﹢1／X=3﹙X＋1／X﹚²＝9X²﹢2 × X ×﹙1／X﹚﹢﹙1／X﹚
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Given the equation 2.5x + 2.5 (x + 2) = 55, can you write a mathematical problem with practice?

Xiao Ming went to buy meat and bought 2.5 Jin of pork and 2.5 Jin of beef, sharing 55 yuan. It is known that one jin of beef is 2 yuan more expensive than one jin of pork. How much does one jin of pork and one jin of beef cost?
Set a catty of pork X Yuan, then a catty of beef (x + 2) yuan
2.5X+2.5（X+2）=55
Remove brackets: 2.5x + 2.5x + 5 = 55
Transfer: 2.5x + 2.5x = 55-5
Merge similar items: 5x = 50
The coefficient is reduced to 1: x = 10
Beef price: 10 + 2 = 12 yuan
A: 10 yuan for a jin of pork and 12 yuan for a jin of beef

The definite equation is 2.5x + 2.5 (x + 2) = 55. Can you compile a mathematical problem in connection with your life?

Xiao Ming went to buy meat and bought 2.5 Jin of pork and 2.5 Jin of beef, sharing 55 yuan. It is known that one jin of beef is 2 yuan more expensive than one jin of pork. How much does one jin of pork and one jin of beef cost?