tính nhanh :
102 x 102 + 10 x 10
K
Khách
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NL
Nguyễn Lê Phước Thịnh
CTVHS
24 tháng 6 2021
Bài 1:
b) Ta có: \(D=\dfrac{-5}{10}\cdot\dfrac{-4}{10}\cdot\dfrac{-3}{10}\cdot...\cdot\dfrac{3}{10}\cdot\dfrac{4}{10}\cdot\dfrac{5}{10}\)
\(=\dfrac{-5}{10}\cdot\dfrac{-4}{10}\cdot\dfrac{-3}{10}\cdot...\cdot0\cdot...\cdot\dfrac{3}{10}\cdot\dfrac{4}{10}\cdot\dfrac{5}{10}\)
=0
HB
16 tháng 5 2018
a)1994x808+1995x192
=1994x808+(1994+1)x192
=1994x808+1994x192+1x192
=1994x(808+192)+192
=1994x1000+192
=1994000+192
=1994192
b)Dãy phép tính đó có:(102-2):2+1=51(số)
Chia 50 số đầu tiên thành 25 nhóm (mỗi nhóm 2 số),ta được:
2-4+6-8+10-12+14-16+18-...+98-100+102
=(2-4)+(6-8)+(10-12)+(14-16)+...+(98-100)+102
=(-2)+(-2)+(-2)+(-2)+...+(-2)+102
=(-2)x25+102
=-50+102
=52
LT
16 tháng 5 2018
a) 1994 x 808 + 1995 x 192
= 1995 x ( 808 + 192 )
= 1995 x 1000
= 1995000
AN
2
10 tháng 10 2018
Có số số hạng là :
( 102 - 2 ) : 4 + 1 = 26 ( số hạng )
Tổng của dãy là :
( 102 + 2 ) x 26 : 2 = 1352
Đáp số : 1352
10 tháng 10 2018
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NL
Nguyễn Lê Phước Thịnh
CTVHS
30 tháng 9 2025
a:
Số số hạng của dãy số 1;2;3;...;102 là:
\(\frac{102-1}{1}+1=\frac{101}{1}+1=101+1=102\) (số)
1-2+3-4+5-6+...+101-102+103
=(1-2)+(3-4)+(5-6)+...+(101-102)+103
\(=\left(-1\right)+\left(-1\right)+\cdots+\left(-1\right)+103\)
\(=\left(-1\right)\cdot\frac{102}{2}+103=103-51=52\)
b: Sửa đề: 2-4+6-8+10-12+...+98-100+102
Số số hạng của dãy số 2;4;6;8;...;98;100 là:
\(\frac{100-2}{2}+1=\frac{98}{2}+1=49+1=50\) (số)
2-4+6-8+10-12+...+98-100+102
=(2-4)+(6-8)+(10-12)+...+(98-100)+102
=(-2)+(-2)+...+(-2)+102
\(=-2\cdot\frac{100}{2}+102\)
=-100+102
=2
c: Số số hạng trong dãy 16;18;20;22;...;64;66 là:
\(\frac{66-16}{2}+1=\frac{50}{2}+1=25+1=26\) (số)
16-18+20-22+...+64-66+68
=(16-18)+(20-22)+...+(64-68)+68
=(-2)+(-2)+...+(-2)+68
\(=\left(-2\right)\cdot\frac{26}{2}+68\)
=68-13
=55
S
30 tháng 12 2021
Giá trị x trong phép tính 10 - 2x = 4 là :
A.5 B.2 C.3 D.7
Kết quả sắp xếp các số -2 ; -3 ; -102 ; -99 theo thứ tự tăng dần là :
A -2 ; -3 ; -99 ; -102
B -102 ; -99 ; -3 ; -2
C -99 ; -102 ; -3 ; -2
D -102 ; -99 ; -2 ; -3
M
11
DN
15 tháng 6 2015
Có khó lắm đâu
Q=2-4+6-8+10-12+...+98-100+102
=2+(6-4)+(10-8)+(14-12)+...+(98-96)+(102-100)
=2+(2+2+2+...+2) (50 chữ số 2)
=2+50
=52
15 tháng 6 2015
Số các số hạng của Q là:
(102-2):2+1=51 số
Vậy có 25 thừa số (-2) và + với 102
Q=(-2)x25+102
Q=(-50)+102
Q=52
VN
Võ Ngọc Phương
VIP
1 tháng 11 2023
\(740:\left(x+10\right)=10^2-2.13\)
\(=>740:\left(x+10\right)=100-26\)
\(=>740:\left(x+10\right)=74\)
\(=>x+10=740:74\)
\(=>x+10=10\)
\(=>x=10-10\)
\(=>x=0\)
2 tháng 8 2018
a)
\(A=\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{2006}-\frac{1}{2009}\)
\(A=\frac{1}{5}-\frac{1}{2009}=\frac{2004}{10045}\)
Các câu kia tương tư
Lưu ý tử số phải bằng hiệu của 2 số ở mẫu ( VD câu b) phải nhân với 4 vào 2 vế để phân số có tử là 4 = 10 - 6 = 14 - 10 =..., cau c0 tương tự )
Học tốt~
NB
1
AH
Akai Haruma
Giáo viên
18 tháng 12 2023
Lời giải:
$=102\times 8,6-8,6\times 2+25\times 4\times 1,4$
$=8,6\times (102-2)+100\times 1,4$
$=8,6\times 100+140=860+140=1000$
102 x 102 + 10 x 10
= 100 x 100 + 10 x 10
= 100 x 100 + 100
= 10000 + 100
= 10100
102 x 102 + 10 x 10
= 100 x 100 + 100
= 100 x (100 + 1)
= 100 x 101
= 10100