2 + 4 + 6 + 8 + .....+ 96 = 4 x
a)
160 : (4 x 8)
160 : 4 : 8
Thực hiện các phép tính sau
a)96 : (3 x 8)
96 : 3 : 8
105 : (5 x 7)
105 : 5 : 7
b)
270 : (9 x 6)
420 : (7 x 3)
144 : (2 x 8)
a)
160 : (4 × 8) = 160 : 32 = 5
160 : 4 : 8 = 40 : 8 = 5
Vậy 160 : (4 × 8) = 160 : 4 : 8.
96 : (3 × 8) = 96 : 24 = 4
96 : 3 : 8 = 32 : 8 = 4
Vậy 96 : (3 × 8) = 96 : 3 : 8.
105 : (5 × 7) = 105 : 35 = 3
105 : 5 : 7 = 21 : 7 = 3
Vậy 105 : (5 × 7) = 105 : 5 : 7.
Nhận xét: a : (b × c) = a : b : c
b)
270 : (9 × 6) = 270 : 9 : 6 = 30 : 6 = 5
420 : (7 × 3) = 420 : 7 : 3 = 60 : 3 = 20
144 : (2 × 8) = 144 : 2 : 8 = 72 : 8 = 9
Điền Đ hoặc S
a) 96 : 4 x 2 = 24 x 2 = 48
b) 96 : 4 x 2 = 96 : 8 = 12
c) 96 : (4 x 2 ) = 96 : 8 = 12
tinh bang cach thuan tien nhat
a 4 / 2 x 4 + 4 / 4 x 6 + 4 / 6 x 8 + ...... + 4 / 96 x 98
=2x(2/2x4+2/4x6+...+2/96x98
=2x(1/2-1/4+1/4-1/6+...+1/96-/98)
=2x(1/2-1/98)
=2x24/49
=48/49
tick nha
tính
B=2*4*6+4*6*8+6*8*10+...+94*96*98+96*98*100
100+98+96+94+...+8+6+4+2
_______________________
100-98+96-94+...+8-6+4-2
\(\frac{100+98+96+94+...+4+2}{100-98+96-94+...+4-2}\)
\(=\frac{\text{[}\left(100-2\right):1+1\text{]}.102:2}{2+2+2+...+2\left(51s\text{ố}2\right)}\)
\(=\frac{5049}{102}=49\frac{1}{2}\)
x-96/ 2 + x- 88/4 +x - 76/6 +x -60/ 8=14
\(\frac{x-96}{2}+\frac{x-88}{4}+\frac{x-76}{6}+\frac{x-60}{8}=14\)
\(\frac{x-96}{2}-2+\frac{x-88}{4}-3+\frac{x-76}{6}-4+\frac{x-60}{8}-5=0\)
\(\frac{x-96}{2}-\frac{4}{2}+\frac{x-88}{4}-\frac{12}{4}+\frac{x-76}{6}-\frac{24}{6}+\frac{x-60}{8}-\frac{40}{8}=0\)
\(\frac{x-96-4}{2}+\frac{x-88-12}{4}+\frac{x-76-24}{6}+\frac{x-60-40}{8}=0\)
\(\frac{x-100}{2}+\frac{x-100}{4}+\frac{x-100}{6}+\frac{x-100}{8}=0\)
\((x-100)\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{6}+\frac{1}{8}\right)=0\)
\(\Rightarrow x-100=0\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{6}+\frac{1}{8}>0\right)\)
\(\Rightarrow x=100\)
Điền Đ, S
a. 96 : 4 x 2 = 24 x 2
= 48
b. 96 : 4 x 2 = 96 : 8
= 12
1/2 + 2/3 + 3/4 + 4/5 + 5/6 + 6/7 + 7/8 + 8/9 + ........+ 95/96 + 96/97 + 97/98 + 98/99 + 99/100 = ?
Số các số hạng là:
(2000 - 100) : 1 + 1 = 1901
Tổng là:
(2000 + 100) x 1901 : 2 = 1996050
Đáp số : 1996050
= [(2000-100)+1]: 2 x (2000+100)= 1996050
Tổng số các số hạng là :
( 2 000 - 100 ) : 1 + 1 = 1 901 ( số hạng )
Tổng của dãy số trên là :
( 2 000 + 100 ) x 1 901 : 2 = 1 996 050
Đáp số : 1 996 050
ủng hộ mk nha các bn ^-^
giải phương trình
x + 2/98 + x + 4/96 = x + 6/94 + x + 8/92
Ta có : \(\frac{x+2}{98}+\frac{x+4}{96}=\frac{x+6}{94}+\frac{x+2}{98}\)
\(\Rightarrow\frac{x+2}{98}+1+\frac{x+4}{96}+1=\frac{x+6}{94}+1+\frac{x+2}{98}+1\)
\(\Rightarrow\frac{x+100}{98}+\frac{x+100}{96}=\frac{x+100}{94}+\frac{x+100}{92}\)
=> \(\left(x+100\right)\left(\frac{1}{98}+\frac{1}{96}\right)=\left(x+100\right).\left(\frac{1}{94}+\frac{1}{92}\right)\)
=> \(\left(x+100\right).\left(\frac{1}{98}+\frac{1}{96}\right)-\left(x+100\right)\left(\frac{1}{94}+\frac{1}{92}\right)=0\)
=> \(\left(x+100\right).\left(\frac{1}{98}+\frac{1}{96}-\frac{1}{94}-\frac{1}{92}\right)=0\Rightarrow x+100=0\left(\text{vì }\frac{1}{98}+\frac{1}{96}-\frac{1}{94}-\frac{1}{92}\ne0\right)\)
=> x = - 100
Vậy x = - 100