tính nhanh 1.2.3....9 - 1.2.3....8 - 1.2.3......8^2
Tính nhanh: 1.2.3...9-1.2.3...8-1.2.3...7.\(8^2\)
Trình bày lời giải đầy đủ giúp mk nha \(please\)
1.2.3...9 - 1.2.3...8 - 1.2.3...7.82
= 1.2.3....8.9 - 1.2.3....8 - 1.2.3...7.8.8
= (1.2.3...8).9 - (1.2.3...8).1 - (1.2.3....7.8).8
= (1.2.3...8). (9 - 1 - 8) = (1.2.3...8) . 0 = 0
Bài 1 Tính nhanh
1.2.3...9-1.2.3...8-1.2.3...7.8.8
1152-(374+1152)+(-65+374)
13-12+11+10-9+8-7-6+5-4+3+2-1
tính: 1.2.3.....9-1.2.3.....8-1.2.3.....82
Tính hợp lý:1.2.3...9-1.2.3...8-1.2.3...82
\(1.2.3...9-1.2.3...8-1.2.3...8^2\)
\(=\left(1.2.3...8\right).9-1.2.3...8-1.2.3..8.8\)
\(=\left(1.2.3....8\right)8-1.2.3.4...8\)
\(=1.2.3...8.8-1.2.3...8.8\)
\(=0\)
Thực hiện phép tính
a, 1.2.3. ... .9-1.2.3. ... .8-1.2.3. ... .8^2
1.2.3.4.....9-1.2.3.4....8-1.2.3...8.8=1.2.3.....8.(9-1)-1.2.3.4....8.8=1.2.3....8.8-1.2.3....8.8=0
Thực hiện phép tính một cách hợp lí :
1.2.3.......9-1.2.3...8-1.2.3....82
1.2.3.......9-1.2.3...8-1.2.3....82
=1.2.3.......9-1.2.3.........8-1.2.3....8.8
= 1.2.3....8(9-1-8)
=1.2.3......8.0
=0
1.2.3. . . 9-1.2.3. . .8-1.2.3. . .7.82
giup minh bai nay nha. Nhanh nhanh cang tot nha.
1.2.3......9-1.2.3....8-1.2.3.....7.82
= 8!..9-8!..1-8!..8
=8!(9-1-8)
=8!.0
=0
k cho mk nhé
1.2.3...9 - 1.2.3...8 - 1.2.3...7.82
= 1.2.3...9 - 1.2.3...8 - 1.2.3...8.8
= 1.2.3...8(9 - 1 - 8)
= 1.2.3...8.0
= 0
Thực hiện phép tính sau đây 1 cách hợp lí: 1.2.3...9 - 1.2.3...8 - 1.2.3...7 . 8^2