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a)
\(25\times189-25\times88-25\)
\(=25\times\left(189-88-1\right)\)
\(=25\times100\)
\(=2500\)
b)
\(38\times66-38\times56+62\times65-62\times55\)
\(=38\times\left(66-56\right)+62\times\left(65-55\right)\)
\(=38\times10+62\times10\)
\(=10\times\left(38+62\right)\)
\(=10\times100\)
\(=1000\)
c)
\(29\times69+29\times31-23\times100\)
\(=29\times\left(69+31\right)-23\times100\)
\(=29\times100-23\times100\)
\(=100\times\left(29-23\right)\)
\(=100\times6\)
\(=600\)
d)
\(\left(519\times288-516\times288\right)\div288\)
\(=288\times\left(519-516\right)\div288\)
\(=288\times3\div288\)
\(=3\)
a)
25×189−25×88−2525×189−25×88−25
=25×(189−88−1)=25×(189−88−1)
=25×100=25×100
=2500=2500
b)
38×66−38×56+62×65−62×5538×66−38×56+62×65−62×55
=38×(66−56)+62×(65−55)=38×(66−56)+62×(65−55)
=38×10+62×10=38×10+62×10
=10×(38+62)=10×(38+62)
=10×100=10×100
=1000=1000
c)
29×69+29×31−23×10029×69+29×31−23×100
=29×(69+31)−23×100=29×(69+31)−23×100
=29×100−23×100=29×100−23×100
=100×(29−23)=100×(29−23)
Bài 1: Ta chỉ cần bỏ ngoặc rồi cộng hai phân số để ra kết quả là số tự nhiên là xong
Bài 2:
A = \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+............+\frac{1}{2003.2004}\)
A = \(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-.............-\frac{1}{2003}+\frac{1}{2003}-\frac{1}{2004}\)
A = \(1-\frac{1}{2004}\)
A = \(\frac{2004}{2004}-\frac{1}{2004}=\frac{2003}{2004}\)
Mk làm mẫu 1 bài nha
Bài 1 :
a, = (1/4+3/4) - (5/13+8/13)+2/11
= 1 - 1 + 2/11
= 2/11
Tk mk nha
a) 31 . { 330 : [178 – 4 . ( 35 – 21 : 3 )]} = 31 . { 330 : [178 – 4 . ( 35 – 7)]}
= 31 . { 330 : [178 – 4 . 28]} = 31 . { 330 : [178 – 112]}
= 31 . { 330 : 66 } = 31 . 5 = 155
b) ( 5 19 . 5 14 ) : 5 32 = 5 33 : 5 32 = 5
a: \(A=38\cdot66-38\cdot56+62\cdot65-62\cdot55\)
\(=38\cdot\left(66-56\right)+62\left(65-55\right)\)
\(=38\cdot10+62\cdot10=10\cdot100=1000\)
b: \(B=11070:15\cdot\left\lbrack356-\left(2021-2011\right)\right\rbrack\)
\(=738\cdot\left\lbrack356-10\right\rbrack=738\cdot346=255348\)
c: C=2015+[(44+2-8):2]
=2015+[(44-6):2]
=2015+38:2
=2015+19
=2034
d: \(D=31:\left\lbrace330:\left\lbrack178-4\cdot\left(35-21:3\right)\right\rbrack\right\rbrace\)
\(=31:\left\lbrace330:\left\lbrack178-4\cdot\left(35-7\right)\right\rbrack\right\rbrace\)
=31:{330:[178-4*28]}
=31:{330:66}
=31:5
=6,2
f: \(F=3597\cdot34+3597\cdot65+3597\)
\(=3597\cdot\left(34+65+1\right)\)
\(=3597\cdot100=359700\)