... hai ng thng song song, ct nhau, trựng nhau? - Lm bi 20 SGK tr 54 + Ba cp ng thng song song: y = 1,5x + v y = 1,5x - y=x+2 v y = x - y = 0,5x - v y = 0,5x + + Cỏc cp ng thng ct nhau: y = 1,5x ... dung * ng thng y = 0,5x + v ng thng y = 0,5x - song song vi nhau, vỡ cú h s a bng nhau, h s b khỏc * ng thng y = 0,5x + v ng thng y = 1,5x + khụng song song, cng khụng trựng Vỡ th chỳng phi ct Tng ... SGK tr54, 55 - Tit sau luyn i s Tun 13 tit 26 LUYN TP I MC TIấU: - Kin thc : + Cng c iu kin hai ng thng y = ax + b (a0) v y = ax + b (a0) ct nhau, song song vi nhau, trựng + HS bit xỏc nh cỏc h...