Tính:
3/5 + 3/11 - (-3/7) + (-2/97) - 1/35 - 3/4 + (-23/44)
Tính hợp lý
\(\frac{3}{5}+\frac{3}{11}-\left(\frac{-3}{7}\right)+\left(\frac{2}{97}\right)-\frac{1}{35}-\frac{3}{4}+\left(\frac{-23}{44}\right)\)
\(\frac{3}{5}+\frac{3}{11}-\left(\frac{-3}{7}\right)+\frac{2}{97}-\frac{1}{35}-\frac{3}{4}+\left(\frac{-23}{44}\right)\)
\(=\frac{3}{5}+\frac{3}{11}+\frac{3}{7}+\frac{2}{97}-\frac{1}{35}-\frac{3}{4}-\frac{23}{44}\)
\(=\left(\frac{3}{5}+\frac{3}{7}-\frac{1}{35}\right)+\left(\frac{3}{11}-\frac{3}{4}-\frac{23}{44}\right)+\frac{2}{97}\)
\(=\left(\frac{21}{35}+\frac{15}{35}-\frac{1}{35}\right)+\left(\frac{12}{44}-\frac{33}{44}-\frac{23}{44}\right)+\frac{2}{97}\)
\(=\frac{35}{35}+\left(\frac{-44}{44}\right)+\frac{2}{97}=1+\left(-1\right)+\frac{2}{97}=\frac{2}{97}\)
\(=\left(\frac{3}{5}+\frac{3}{7}-\frac{1}{35}\right)+\left(\frac{3}{11}-\frac{3}{4}-\frac{23}{44}\right)+\frac{2}{97}\)
\(=\left(\frac{21}{35}+\frac{15}{35}-\frac{1}{35}\right)+\left(\frac{12}{44}-\frac{33}{44}-\frac{23}{44}\right)+\frac{2}{97}\)
\(=-1+1+\frac{2}{97}\)
\(=\frac{2}{97}\)
=[3/5+(-3/7)-1/35]+[3/11-3/4-(-23/44)]+2/97
=[21/35+(-15/35)-1/35]+[12/44-33/44-(-23/44)+2/97
=(-1)+1+2/97
=0+2/97
=2/97
3/5+3/11-[-3/7]+2/97-1/35-3/4+22/44
\(\frac{3}{5}+\frac{3}{11}-\left(\frac{-3}{7}\right)+\frac{2}{97}-\frac{1}{35}-\frac{3}{4}+\frac{22}{44}\)
\(=\frac{3}{5}+\frac{3}{11}+\frac{3}{7}+\frac{2}{97}-\frac{1}{35}-\frac{3}{4}+\frac{22}{44}\)
\(=\frac{3}{5}+\frac{3}{7}-\frac{1}{35}+\frac{3}{11}-\frac{3}{4}+\frac{22}{44}+\frac{2}{97}\)
\(=\left(\frac{3}{5}+\frac{3}{7}-\frac{1}{35}\right)+\left(\frac{3}{11}-\frac{3}{4}+\frac{22}{44}\right)+\frac{2}{97}\)
\(=\left(\frac{21}{35}+\frac{15}{35}-\frac{1}{35}\right)+\left(\frac{12}{44}-\frac{33}{44}+\frac{22}{44}\right)+\frac{2}{97}\)
\(=\frac{35}{35}+\frac{1}{44}+\frac{2}{97}\)
\(=1+\left(\frac{1}{44}+\frac{2}{97}\right)\)
\(=1+\left(\frac{97}{4268}+\frac{88}{4268}\right)\)
\(=1+\frac{185}{4268}=1\frac{185}{4268}\)
Chúc bạn học tốt
Trả lời:
\(\frac{3}{5}+\frac{3}{11}-\left(\frac{-3}{7}\right)+\frac{2}{97}-\frac{1}{35}-\frac{3}{4}+\frac{22}{44}\)
\(=\frac{3}{5}+\frac{3}{11}+\frac{3}{7}+\frac{2}{97}-\frac{1}{35}-\frac{3}{4}+\frac{22}{44}\)
\(=\left(\frac{3}{5}+\frac{3}{7}-\frac{1}{35}\right)+\left(\frac{3}{11}-\frac{3}{4}+\frac{22}{44}\right)+\frac{2}{97}\)
\(=1+\frac{1}{44}+\frac{2}{97}\)
\(=\frac{4453}{4268}\)
3/5+3/11+3/7+2/97-1/35-3/4+22/44
(3/5+3/7-1/35)+(3/11-3/4+22/44)+2/97
(21/35+15/35-1/35)+(12/44-33/44+22/44)+2/97
1+1/44+2/97
4453/4268
Tính nhanh
A=2/1*5+2/5*9+2/9*13+...+2/97*101+2/101*105
B=4/2*5+4/5*2+4/8*11+...+4/44*47+4/47*50
C=3/1*3*5+3/3*5*7+3/5*7*9+...+3/19*21*23+3/21*23*25
A = 2/1*5 + 2/5*9 + ... + 2/101*105
= 1/2(4/1*5 + 4/5*9 + ... + 4/101*105)
= 1/2(1 - 1/5 + 1/5 - 1/9 + ... + 1/101 - 1/105)
= 1/2(1 - 1/105)
= 1/2 * 104/105 = 52/105
Sửa câu b. Phân số thứ 2 phải là 4/5*8
B = 4/2*5 + 4/5*8 + ... + 4/47*50
= 4/3(3/2*5 + 3/5*8 + ... + 3/47*50)
= 4/3(1/2 - 1/5 + 1/5 - 1/8 + ... + 1/47 - 1/50)
= 4/3(1/2 - 1/50)
= 4/3 * 24/50 = 16/25
Thực hiện phép tính hợp lý
A= (6-2/3+1/2)-(5+5/3-3/2)-(3-7/3+5/2)
B= 3/5+3/11+-2/97-1/35-3/4+-23/24
A = 6 -2/3 + 1 /2 - 5 -5/3 +3/2 -3 + 7/3 - 5/2
= (6 - 5 - 3) - ( 2/3 -5/3 + 7/3 ) + ( 1/2 +3/2 - 5/2)
= -2 + 0 -1/2 = -5/2
Tính hợp lí:
a)\(\left(\frac{-1}{2}\right)-\left(\frac{-3}{5}\right)+\left(\frac{-1}{9}\right)+\frac{1}{127}\)\(-\left(+\frac{7}{18}\right)+\frac{4}{35}-\left(\frac{-2}{7}\right)\)
b)\(\frac{3}{5}+\frac{3}{11}-\left(\frac{-3}{7}\right)+\)\(\left(\frac{2}{97}\right)-\frac{1}{35}-\frac{3}{4}+\left(\frac{-23}{44}\right)\)
B= \(\frac{3}{5}+\frac{3}{11}+\frac{-2}{97}-\frac{1}{35}-\frac{3}{4}+\frac{-23}{44}\)
giúp mik với nhé!
^3^
Tính nhanh
1)35-7.(5-18)
2)5+9+13+17+21-7-11-15-19-23
3)100+98+96+...+4+2-97-95-....-3-1
tính bằng cách hợp lí:
\(\frac{3}{5}+\frac{3}{11}+\frac{-3}{7}+\frac{-2}{97}-\frac{1}{35}-\frac{3}{4}+\frac{-23}{24}\)
C= 4+44+444+......+4444444444
D=5+55+555+........+5555555555
E=1*3^2+3*5^2+51*7^2+.....+97*99^2
F=1*3*5-3*5*7+5*7*9-7*9*11+.......-97*99*101
Ta có:
\(C= 4+44+444+......+4444444444\)
\(C= 4.(10.1+9.10+8.100+7.1000+...+1.1000000000\)
\(C= 4.(100+90+800+7000+60000+500000+4000000+30000000+200000000+1000000000)\)
\(C=4.12345678900\)
\(C=4938271600\)
Tương tự.