100 + 98 + 96 + 94...... + 2 - 97 - 95 - 93 - 92 - 91...- 1
A=100+98+96+94+92+...+2-99-97-95-93-91-...-1 = ?
100-99+98-97+96-95+94-93+92-91+90
= ?
TÍNH NHANH
\(100-99+98-97+96-95+94-93+92-91+90\)
\(=\left(100-99\right)+\left(98-97\right)+\left(96-95\right)+\left(94-93\right)+\left(92-91\right)+90\)
\(=1+1+1+1+1+90\)
\(=95\)
Tính nhanh : 100 - 99 + 98 - 97 + 96 - 95 + 94 - 93 + 92 - 91 + 90
thấy (100-99)+(98-97)+(96-95)+(94-93)+(92-91)+90
=1+1+1+1+1+90
=95
100 - 99 + 98 - 97 + 96 - 95 + 94 - 93 + 92 - 91 + 90 = 95
100-99+98-97+96-95+94-93+92-91+90
=1+1+1+1+1+90
=95
Tính bằng cách thuận tiện: 100 - 99 +98 -97 + 96 -95 +94 - 93 + 92 - 91 + 90 = ?
100 - 99 +98 -97 + 96 -95 +94 - 93 + 92 - 91 + 90 =?
=> 1+1+1+1+1+90
=>5+90 = 95
tick nhé
95 nha
~HT~
91+92+93+94+95+96+97+98+99=
tính 99+98+97+96+95+94+93+92+91=
tính = 99+98+97+96+95+94+93+92+91=
tinh nhanh : 100-99+98-97+96-95+94-93+92-91+90
giup minh voi
91+92+93+94+95+96+97+98+99= bao nhiêu
91+92+93+94+95+96+97+98+99
=(91+99)+(92+98)+(93+97)+(94+96)+95
= 190 + 190 + 190 + 190 + 95
= 760 + 95
= 855
= (99 + 91) + ( 98 + 92 ) + ( 97+ 93 ) + ( 94 + 96 ) + 95
= 190 + 190 + 190 +190 +95
= 760 + 95
= 855