Câu 1: Tìm x
a, X + 12 = 12 + 6 14 – X = 14 – 2
b, X – 21 = 33 - 21 65 – X = 48 + 17
Câu 2: Tìm x
a, X + 25 = 100 - 25 700 – X = 300 + 200
b, X + 125 = 100 + 125 X – 48 = 65 – 28
Câu 3: Tìm y
a, 45 + y = 67 +17 27 + y = 44 + 18
b, y x 4 = 8 x 2 2 x y = 2 x 9
c, 5 x y = 30 : 3 y x 3 = 24 + 6
Câu 4: Tìm y
a, 123 – y = 456 - 345 y + 345 = 657 + 170
b, y – 112 + 12 = 574 y – 231 = 405 + 15
Câu 5 : Tìm x
a, 170 – X = 46 + 48 65 + 59 + X = 179
b, X – 21 = 33 -21 65 – X = 48 + 17
\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)
Tìm xToán lớp 2