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Gọi số học sinh lớp 9A là a ( học sinh ) số học sinh lớp 9B là b ( học sinh ).
Tổng số cây bàng là 204 cây => Ta có :
2.a + 4.b = 204
<=>a + 2b = 102
Tổng số cây phượng là 233 cây => Ta có:
4a + 3b = 233
Theo đề bài ,ta có :
\(\hept{\begin{cases}a+2b=102\\4a+3b=233\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}a=102-2b\\4a+3b=233\end{cases}\Rightarrow\hept{\begin{cases}a=32\\b=35\end{cases}\left(hs\right)}}\)
Vậy số học sinh lớp 9A là 32
số học sinh lớp 9B là 35
3x2-12+45=0
3x2=-33
x2=-1
PT vô nghiệm
Chuc bạn hok tốt !!!!
Nhớ tích cho minh
11. There wouldn't be serious water pollution if the factory treated its waste well.
12. If I didn't learn ten new items of vocabulary a day, I couldn't speak English with foreigners.
13. If she didn't go to an English speaking club every week, she couldn't speak English fluently.
14. I could look the word up if I had got a dictionary.
15. Nick could find the way if he had got a map.
16. We could take a trip to London if we had enough money.
17. He wouldn't cough a lot if he didn't smoke forty cigarettes a day.
11. There wouldn't be serious water pollution if the factory treated its waste well.
12. If I didn't learn ten new items of vocabulary a day, I couldn't speak English with foreigners.
13. If she didn't go to an English speaking club every week, she couldn't speak English fluently.
14. I could look the word up if I had got a dictionary.
15. Nick could find the way if he had got a map.
16. We could take a trip to London if we had enough money.
17. He wouldn't cough a lot if he didn't smoke forty cigarettes a day.
Mấy câu sau bn tự làm nhé . Tham Khảo
