i_love_thtt

Nếu 5a+2b+3c=0.
CM rằng PT: $ax^2+bx+c=0$ luôn có nghiệm.

= a^{2} -4bc
ta di cm 0,rut b tu dieu kien 5a+2b+3c=0
thay vao(muc dich de lam giam so bien),co dinh c,dao ham theo bien a,..... tu giai tiep
pp nay dc goi la pp dao ham theo tug bien',neu ban chua ro thi hoi them cac thay ve pp nay .pp nay rat hay
giai dc nhiu bai tap

sao ko ai giai het za. troi

nghi sao ak,q? do' 270k mua xog an mi ca? tuan luon hix t co cuon bat sg cac ban dg noi ne q? cua tran phuong cac pp va ki thuat cm bdt...,ma can j hoc q? do' len mag kiem tai lieu. ve hoc het say?, t hoc c.toan lekhiet,quang ngai ai can q? do thi lhe vs t i_love_thtt