D=5/6.37+1/6.43+6/7.43+10/7.59 ;E=8/9.37+2/9.47+3/10.47+9/10.59 .tính D/E
a,1+2-3-4+5+6-7-8+9+.......+994-995-996+997+998
b,(1+1/2) (1+1/3) (1+1/4) .....(1+1/2023)
c d=5/6.37+1/6.43+6/7.43+10/7.59
\(b.\left(1+\frac12\right)\left(1+\frac13\right)\left(1+\frac14\right)\ldots\left(1+\frac{1}{2023}\right)\)
\(=\frac32\cdot\frac43\cdot\frac54\cdot\ldots\cdot\frac{2024}{2023}\)
\(=\frac{3\cdot4\cdot5\cdot\ldots\cdot2024}{2\cdot3\cdot4\cdot\ldots\cdot2023}\)
\(=\frac{2024}{2}=1012\)
\(c.D=\frac{5}{6\cdot37}+\frac{1}{6\cdot43}+\frac{6}{7\cdot43}+\frac{10}{7\cdot59}\)
\(D=7\cdot\left(\frac{5}{37\cdot42}+\frac{1}{42\cdot43}+\frac{6}{43\cdot49}+\frac{10}{49\cdot59}\right)\)
\(D=7\cdot\left(\frac{1}{37}-\frac{1}{42}+\frac{1}{42}-\frac{1}{43}+\frac{1}{43}-\frac{1}{49}+\frac{1}{49}-\frac{1}{59}\right)\)
\(D=7\cdot\left(\frac{1}{37}-\frac{1}{59}\right)\)
\(D=7\cdot\frac{22}{2183}\)
\(D=\frac{154}{2183}\)
a: 1+2-3-4+5+6-7-8+9+10-11-12+...+994-995-996+997+998
=(1+2-3-4)+(5+6-7-8)+(9+10-11-12)+...+(993+994-995-996)+(997+998)
=(-4)+(-4)+...+(-4)+(997+998)
\(=-4\cdot\frac{996-1+1}{4}+997+998\)
=-996+997+998
=999
b: \(\left(1+\frac12\right)\left(1+\frac13\right)\cdot\ldots\cdot\left(1+\frac{1}{2023}\right)\)
\(=\frac32\cdot\frac43\cdot\ldots\cdot\frac{2024}{2023}\)
\(=\frac{2024}{2}=1012\)
c: \(D=\frac{5}{6\cdot37}+\frac{1}{6\cdot43}+\frac{6}{7\cdot43}+\frac{10}{7\cdot59}\)
\(=\frac{35}{37\cdot42}+\frac{7}{42\cdot43}+\frac{42}{43\cdot49}+\frac{70}{49\cdot59}\)
\(=7\left(\frac{5}{37\cdot42}+\frac{1}{42\cdot43}+\frac{6}{43\cdot49}+\frac{10}{49\cdot59}\right)\)
\(=7\left(\frac{1}{37}-\frac{1}{42}+\frac{1}{42}-\frac{1}{43}+\frac{1}{43}-\frac{1}{49}+\frac{1}{49}-\frac{1}{59}\right)\)
\(=7\left(\frac{1}{37}-\frac{1}{59}\right)=7\cdot\frac{22}{37\cdot59}=\frac{154}{2183}\)
Tính D= 5/6.37+ 1/6.43+ 6/7.43+ 10/7. 59
1/7. 7/3 +5/2 . 3/7.59/6. 1/7
1/7 . 7/3 + 5/2 . 3/7 . 59/6 . 1/7
= 1/7 . (7/3 + 5/3 . 3/7 . 59/6)
= 1/7 . 131/14
= 131/98
Tìm tỉ số A/B biết
A=4/7.31+6/7.41+9/10.41+7/10.57 và B=7/19.31+5/7.43+3/23.43+11/23.57
Cho
A=3/(4.19)+5/(6.19)+13/(6.37)+13/(13.37) +23/13.75
B=5/(7.6)+8/(7.29)+10/(13.29)+14/(13.53)+22/25.53
Tính A/B
2X.(9:6-7.43+x)
ĐỨA NÀO GIẢI ĐƯỢC KÍCH VÀ KẾT BẠN
Bài 1: Thiện phép tính (Tính hợp lý nếu có thể)
a.-35.12 – 8.35 b. 23.(-7) – 7.59 + (-18).7 b. 115 – (-12 + 29)
c. 3.(-7)2 + 5.(-4)3
a)-35.12-8-35=-35(12+8)=-35.20=-700
b)23.(-7)-7.5+(-18).7=-7(23+59+18)=-7.100=-700
c)115-(-12+29)=115+12-29=98
d)\(3\left(-7\right)^2+5\left(-4\right)^3=3.7^2-5.4^3=3.49-5.64=147-320-173\)
\(a,-35.12-8.35\)
\(=\left(-35\right)\left(12+8\right)\)
\(=-700\)
\(b,-23.7-7.59-18.7\)
\(=7\left(-23-59-18\right)\)
\(7.\left(-100\right)=-700\)
\(b,115-\left(-12+29\right)\)
\(=115+12-29\)
\(=98\)
\(c,3.\left(-7\right)^2+5.\left(-4\right)^3\)
\(=3.49-5.64\)
\(=147-320\)
\(=-173\)
A (-6.37 * 0.4)*2.5
(-6.37 * 0.4)*2.5= -2.548*2.5=-6.37
an may di bn ko thi nhan don vs da thuc
Tìm các số tự nhiên n, biết:
a) 33.2n = 432
b) 784 : 7n = 24
c) 9 < 3n : 3 < 81
d) 2. 3n = 6.37
e) 34. 3n = 93
f) 2n+2 - 2n = 96
a) n = 14
b) n = 2
c) n = 4
d) n = 8
e) n = 2
f) n = 5