tinh nhanh: A; 42 x 65 / 6 x 5 B; 48 x 63 / 9 x 8 C; 9 x 71 / 213 x 189
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=32.233+67.233+68.233
=233.(68+32+67)
=233.167
=38911
hok tốt k nhé bạn
\(32\times\left(233+67\right)+68\times233\)
=\(32\times233+67\times233+68\times233\)
=\(233\left(32+67+68\right)\)
=\(233\times167\)
=\(38911\)
#hoctot
2: \(=\left(\dfrac{-4}{9}-\dfrac{1}{9}-\dfrac{5}{9}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)+\dfrac{1}{5}=\dfrac{1}{5}-\dfrac{1}{9}=\dfrac{4}{45}\)
4: \(=\dfrac{3}{11}\cdot\dfrac{1}{3}\cdot\dfrac{121}{15}=\dfrac{11}{15}\)
6: \(=\dfrac{6}{7}\left(\dfrac{8}{13}+\dfrac{9}{13}-\dfrac{3}{13}\right)=\dfrac{6}{7}\cdot\dfrac{16}{13}=\dfrac{96}{91}\)
8: \(=\dfrac{9}{25}\cdot\dfrac{-53}{3}-\dfrac{9}{25}\cdot\dfrac{22}{3}=\dfrac{9}{25}\cdot\left(-25\right)=-9\)
= 4,12 x 0,1 + 3,28 x 0,1 + 2,6 x 0,1
= 0,1 x ( 4,12 + 3,28 + 2,6)
= 0,1 x 10
= 1
9x24 + 25
= 9 x 24 +24 x 1 + 1
= 24 x ( 9 + 1) + 1
= 24 x 10 + 1
= 240 + 1 = 241
425 x 32 + 69 x 425 - 425
= 425 x 32 + 69 x 425 - 425 x 1
= 425 x (32+69-1)
= 425 x 100
= 42500
`#3107`
\(\text{32684+41325+316+675}\\ =\left(32684+316\right)+\left(41325+675\right)\\=33000+42000\\ =75000\)
\(33\times77+66\times77+77\)
\(=77\times\left(33+66+1\right)\)
\(=77\times100\)
\(=7700\)
c) \(\dfrac{1}{15}+\dfrac{1}{35}+\dfrac{1}{63}+\dfrac{1}{99}+\dfrac{1}{143}=\dfrac{1}{2}\left(\dfrac{2}{3.5}+\dfrac{2}{5.7}+\dfrac{2}{7.9}+\dfrac{2}{9.11}+\dfrac{2}{11.13}\right)\)
\(=\dfrac{1}{2}\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{11}-\dfrac{1}{13}\right)=\dfrac{1}{2}\left(\dfrac{1}{3}-\dfrac{1}{13}\right)=\dfrac{1}{2}.\dfrac{10}{39}=\dfrac{5}{39}\)
e) \(\dfrac{1}{5}.\dfrac{4}{7}+\dfrac{3}{7}.\dfrac{1}{5}-\dfrac{1}{5}=\dfrac{1}{5}\left(\dfrac{4}{7}+\dfrac{3}{7}\right)-\dfrac{1}{5}=\dfrac{1}{5}.1-\dfrac{1}{5}=0\)
minh cung co cau hoi giong ban ne nhung van chua co cau tra loi
mn oi giup minh voi con 2 phut nua la minh phai nop bai rui huhuhu help me