X− + X− +X− = X− + X− +X− B, 2 1 4 3X− +X− = X− +X−A, 5 4 3 100 101 102100 101 102 5 4 37 8 5 6HD
Bài 3: Tìm x, biết: x− + x− +x− = x− + x− +x− b, 2 1 4 3x− +x− = x− +x−a, 5 4 3 100 101 102100 101 102 5 4 37 8 5 6HD: a, 5 4 3 100 101 102x− x− x− x− x− x−= − + − + − = − + − + − 1 1 1 1 1 1x− +x− +x− = x− +x− +x−=> 105 105 105 105 105 105=> x−105= = =0 x 105b, => − + − = − + − = + = +x− x− x− x− x− x− x− x−2 1 4 3 9 9 9 9 1 1 1 1 7 8 5 6 7 8 5 6=> x− = = =9 0 x 9