... = 12 D x = 10 Cõu 41: S hc sinh ca hai lp 7A v 7B t l v S hc sinh lp 7B nhiu hn s hc sinh lp 7A l hc sinh Vy s hc sinh lp 7A v 7B ln lt l : A 32HS; 37HS B 45HS; 40HS C 30HS; 35HS D 40HS; 45HS ... (x) Tn s (n) Cỏc tớch (x.n) 100 100 70 30 X =? N = 300 A X = 5, B X = 4,1 Cõu 26: Giỏ tr ca a thc C ti x = 2; y = -1 l: A -6 B 14 C X = 4,5 D X = 5,15 C D -14 Cõu 27: Trờn mt phng ta Oxy ly hai ... tam giỏc ABC cõn ti A, cú A =70 o S o gúc B l : A 50o B 60o C 55o D 75 o Cõu 17: B ba no s cỏc b ba sau khụng phi l di ba cnh ca tam giỏc A 6cm; 8cm; 10cm B 5cm; 7cm; 13cm C 2,5cm; 3,5cm; 4,5cm...