1:" thuc hien phep tinh : (-1)+2-3+4-....-99+100
THUC HIEN PHEP TINH
1+1^3+1^4+... +1^98 +1^99
help me mik like
1 + 13 + 14 + ............. + 198 + 199 (98 số hạng)
= 1 + 1 + 1 + 1 + .......... + 1 (98 số hạng)
= 98 . 1
= 98
thuc hien phep tinh (100- 1 ) (100-2)..........(100-3)
( 100 - 1 ) ( 100 - 2 ) ( 100 - 3 )
= 99 . 98 . 97
= 941094
so (100-3) mik ghi sai sửa thành số (100-n)
khong thuc hien phep tinh , hay so sanh : 99 x 99 va 98 x 100
Ta có: 99x99=99x(98+1) = 99x98+99
98x100= 98x(99+1) = 98x99+98
Ta có: 98x99=98x99 mà 99> 98 => 99x99>98x100
thuc hien phep tinh
a) S1=2+2^2+2^3+...+2^90
b)S2= (-2) +(-2)^2 +(-2)^3+...(-2)^100
c)S3=2^100-2^99-2^98-2^97-...-2^2-2-1
d)S4=1-3+5-7+...+2001-2003+2005-
\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)
thuc hien phep tinh:-39.(5-99)+99.(10-99)
thuc hien phep tinh:-39.(5-99)+99.(10-99)
-39 . ( 5 - 99 ) + 99 . ( 10 - 99 )
= ( -39 ) . ( -94 ) + 99 . ( -89 )
= 3666 + ( -8811 )
= -5145
\(-39\cdot\left(5-99\right)+99\cdot\left(10-99\right)\)
\(=-39\cdot5-\left(-39\right)\cdot99+99\cdot10-99\cdot99\)
\(=-39\cdot5+39\cdot99+99\cdot10-99\cdot99\)
\(=-39\cdot5+99\cdot\left(39+10-99\right)\)
\(=-39\cdot5+99\cdot50\)
\(=-195+4950\)
\(=4755\)
thuc hien phep tinh
m=1+(-2)+3+(-4)+...+(-2016)+2017
m = 1 + ( -2 ) + 3 + ( -4 ) + ....... + ( - 2016 ) + 2017
m = [ 1 + ( - 2 ) ] + [ 3 + ( -4 ) ] + ...... + [ 2015 + ( -2016 ) + 2017
m = ( -1 ) + ( -1 ) + ...... + ( -1 ) + 2017
có 1008 số -1
m = ( -1 ) x 1008 + 2017
m = ( -1008 ) + 2017
, = 1009
Ta có :
m = 1 + ( -2 ) + 3 + ( -4 ) + ....... + ( - 2016 ) + 2017
m = [ 1 + ( - 2 ) ] + [ 3 + ( -4 ) ] + ...... + [ 2015 + ( -2016 ) + 2017
m = ( -1 ) + ( -1 ) + ...... + ( -1 ) + 2017 [ có 1008 số -1 ]
m = ( -1 ) x 1008 + 2017
m = ( -1008 ) + 2017
m = 1009
1/4 - 1/3+ 5/12 Thuc hien cac phep tinh (tinh hop li neu co the)
\(\dfrac{1}{4}-\dfrac{1}{3}+\dfrac{5}{12}\\ =\dfrac{3}{12}-\dfrac{4}{12}+\dfrac{5}{12}\\ =\dfrac{3-4+5}{12}\\ =\dfrac{4}{12}\\ =\dfrac{1}{3}\)
thuc hien phep cac phep tinh sau:
a, (1-1/2).(1-1/3).(1-1/4)...(1-1/100)
b, (1+1/1.3).(1+1/2.4).(1+1/3.5)...(1+1/99.101)