Cho pt: x² - (m + 2) + 7m - 2m²  - 3 = 0 (với x là ẩn số) (1)

a) Chứng tỏ phương trình (1) luôn có 2 nghiệm phân biệt.

b) Tìm m để phương trình (1) có hai nghiệm x_{1 ,} x₂ thỏa hệ thức:
      2(x₁² - x₂²) - 5x₁x₂ = 2

WISH STATEMENT 1. Mai is rude to me. I wish …………………………………………… 2. Their friends don’t play football with them. They wish …………………........................................ 3. They can’t play football. I wish…………………............................................... 4. What a pity that we depend on our parents . We wish …………………........................................... 5. They are sorry they will play football after dinner. They wish ………………............................................ 6. Lan doesn’t write to us regularly Lan wishes …………….......................................... 7. Nam comes home late. Nam wishes………....................................................... 8. My sister talks in Miss Loan’s class . My sister wishes …………..................................... 9. I am the shortest student in my school. I wish ………………….................................... 10. His brothers always behave badly with new students. He wishes ………….............................................. 11. My boyfriend leaves me on the street. I wish ………………….......................................... 12. I never see a ghost in my life . I wish …………………................................... 13. I hardly correspond with you once a week I wish …………………......................................... 14. He is sorry that he gets bad marks . He wishes ……………….................................. 15. The weather ’s so hot . I wish ………………........................................... 16. Minh always speaks English badly. They wish ………………………………………. 17. They will make a lot of mistakes. I wish ________________________________ 18. What a pity he rarely writes me any word. I wish_____________________________