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a) 17 x 4 - 4 + 4 x 1
= 4 x ( 17 - 1 + 1 )
= 4 x 17
=428
b) 1 x 1 + 1 x 13 + 1
= 1 x ( 1 + 13 + 1 )
=1 x 15
=15
2 x 6 + 2 x 6 + 2
=2 x ( 6 + 6 + 1 ))
=2 x 13
=26
17 x 4 - 4 + 4 x 1
=17 x 4 + 4 x 1 - 4
=4 x (17+1) - 4
=4 x 18 - 4
=72 - 4 = 68
2 x 5 - 5 + 5 x 2
=2 x 5 + 5 x 2 - 5
=10+10-5=15
b, 1x1+1x13+1
= 1+13+1 = 15
2x6+2x6+2
=12+12+2=26
bạn có chép sai đề k z ???
\(a,\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)
\(=\frac{1}{2}-\frac{1}{6}=\frac{1}{3}\)
\(b,\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{4}\right)=\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\)
\(=\frac{1\times2\times3}{2\times3\times4}=\frac{1}{4}\)
a, 2x9x5x7x4x25
=2x5x4x25x9x7
=10x100x63
=63000
b,6x14x5x25x3x4
=6x5x3x4x25x14
=90x100x14
=9000x14
=126000
~HT~
Trả lời :
25 x 8 x 50 x 125 x 4 x 2
= ( 25 x 4 ) x ( 8 x 125 ) x ( 50 x 2 )
= 100 x 1000 x 100
= 100 000 000
~HT~
#sad
a, 2.9.5.7.4.25=(2.5).(25.4).(7.9)
=10.100.63=63000
câu b làm tương tự tích giúp mình nha
24 x \(\frac{4}{6}\)x \(\frac{3}{4}\) = \(\frac{24}{1}\) x \(\frac{4}{6}\) x \(\frac{3}{4}\)
= \(\frac{24x4x3}{1x6x4}\)
= \(\frac{6x4x4x3}{1x6x4}\)
= 3
\(a.\frac{3}{7}.\frac{5}{6}+\frac{5}{6}.\frac{4}{7}=\left(\frac{3}{7}+\frac{4}{7}\right).\frac{5}{6}=1.\frac{5}{6}=\frac{5}{6}\)
\(b.\frac{1}{6}:\frac{4}{5}+\frac{1}{8}:\frac{4}{5}=\left(\frac{1}{6}+\frac{1}{8}\right):\frac{4}{5}=\left(\frac{4}{24}+\frac{3}{24}\right):\frac{4}{5}=\frac{7}{24}:\frac{4}{5}=\frac{7.5}{24.4}\)\(=\frac{35}{96}\)
\(c.\frac{1}{6}:\frac{4}{5}-\frac{1}{8}:\frac{4}{5}=\left(\frac{1}{6}-\frac{1}{8}\right):\frac{4}{5}=\left(\frac{4}{24}-\frac{3}{24}\right):\frac{4}{5}\)\(=\frac{1}{24}:\frac{4}{5}=\frac{1.5}{24.4}=\frac{5}{96}\)
a) \(\frac{3}{7}\cdot\frac{5}{6}+\frac{5}{6}\cdot\frac{4}{7}\)
\(=\left(\frac{3}{7}+\frac{4}{7}\right)\cdot\frac{5}{6}\)
\(=1\cdot\frac{5}{6}\)
\(=\frac{5}{6}\)
b) \(\frac{1}{6}:\frac{4}{5}+\frac{1}{8}:\frac{4}{5}\)
\(=\left(\frac{1}{6}+\frac{1}{8}\right):\frac{4}{5}\)
\(=\frac{7}{24}:\frac{4}{5}\)
\(=\frac{35}{96}\)
c) \(\frac{1}{6}:\frac{4}{5}-\frac{1}{8}:\frac{4}{5}\)
\(=\left(\frac{1}{6}-\frac{1}{8}\right):\frac{4}{5}\)
\(=\frac{1}{24}:\frac{4}{5}\)
\(=\frac{5}{96}\)
Bài 5: Tính bằng cách thuận tiện nhất
a) 189 x 6 + 189 x 5 - 189
=189x(6+5-1)
=189x10
=1890
b) 25 x 86 x 4
=25x4x86
=100x86
=8600
HT
AÁDQWERTYUI