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Câu a bạn chưa giải nhanh, bạn hãy tách nó ra rồi làm theo cách nhanh nhất, những thôi mk k bn trước....còn câu a ai trả lời đc mk sẽ , trả lời câu a thôi cx đc
a. 9999.997 + 9999 + 9999 + 9999
= 9999.(997 + 1 + 1 + 1)
= 9999 . 1000
= 9999000
b. (456 . 11 + 912) . 37 : 13 : 74
= (5016 + 912) . 37 : 13 : 74
= 219336 : 13 : 74
= 16872 : 74
= 228
c. 864 . 48 - 432 . 96 : 864 . 48 . 432
= (864 . 48 - 432 . 96) : (864 . 48 . 432)
= 0 : (864 . 48 . 432)
= 0
a. 9999.997 + 9999 + 9999 + 9999
= 9999.(997 + 1 + 1 + 1)
= 9999 . 1000
= 9999000
b. (456 . 11 + 912) . 37 : 13 : 74
= (5016 + 912) . 37 : 13 : 74
= 219336 : 13 : 74
= 16872 : 74
= 228
c. 864 . 48 - 432 . 96 : 864 . 48 . 432
= (864 . 48 - 432 . 96) : (864 . 48 . 432)
= 0 : (864 . 48 . 432)
= 0
misa
Đặt tên biểu thức là A ta có :
\(A=\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+....+\frac{1}{90}+\frac{1}{110}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{10}-\frac{1}{11}\)
\(=\left(\frac{1}{2}-\frac{1}{11}\right)+\left(\frac{1}{3}-\frac{1}{3}\right)+.....+\left(\frac{1}{10}-\frac{1}{10}\right)\)
\(=\left(\frac{1}{2}-\frac{1}{11}\right)+0+......+0\)
\(=\frac{11}{22}-\frac{2}{22}=\frac{9}{22}\)
\(\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+...+\frac{1}{10.11}\)
=\(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{10}-\frac{1}{11}\)
=\(\frac{1}{2}-\frac{1}{11}\)
=\(\frac{9}{22}\)
2+6+8+10+14+18+....+30+34+38+42+46
=(2+46)+(6+42)+(10+38)+....+(22+26)
=48x6
=288
\(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+....+\frac{1}{90}+\frac{1}{110}\)
\(=\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+.....+\frac{1}{9.10}+\frac{1}{10.11}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+.......+\frac{1}{9}-\frac{1}{10}+\frac{1}{10}-\frac{1}{11}\)
\(=\frac{1}{2}-\frac{1}{11}\)
\(=\frac{9}{22}\)
\(=\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+....+\frac{1}{10\cdot11}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{10}\cdot-\frac{1}{11}\)
\(=\frac{1}{2}-\frac{1}{11}\)
\(=\frac{9}{22}\)
\(\dfrac{16\times25+44\times100}{29\times96+124\times48}\)
\(=\dfrac{16\times25+44\times25\times4}{29\times2\times48+124\times48}\)
\(=\dfrac{25\times16+176\times25}{48\times\left(58+124\right)}\)
\(=\dfrac{25\times192}{48\times182}\)
\(=\dfrac{50}{91}\)
a)\(\frac{864.48-432.96}{864.48+432}\)
=\(\frac{864.48-432.2.48}{864.48+432}\)
=\(\frac{864.48-864.48}{864.48+432}\)
=\(\frac{0}{864.48+432}\)
=0
864x48-432x96/864x48+432=2x432x48-432x48x2/864x48+432=0/864x48+432=0.
**** mình nha
