# Rep mik với ạ! Tks nhìu U^U

Question

Rep mik với ạ! Tks nhìu U^U

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2 years 2021-03-23T06:57:25+00:00 3 Answers 31 views 0

1. Đáp án:

C4: $$\dfrac{1}{{64}}$$

Giải thích các bước giải:

$$\begin{array}{l} C1:\\ 3 – \dfrac{1}{4} + \dfrac{2}{3} – 5 – \dfrac{1}{3} + \dfrac{6}{5} – 6 + \dfrac{7}{4} – \dfrac{3}{2}\\ = \left( {3 – 5 – 6} \right) + \left( { – \dfrac{1}{4} – \dfrac{3}{2} + \dfrac{7}{4}} \right) + \left( {\dfrac{2}{3} – \dfrac{1}{3}} \right) + \dfrac{6}{5}\\ = – 8 + \left( {\dfrac{{ – 1 – 6 + 7}}{4}} \right) + \left( {\dfrac{{2 – 1}}{3}} \right) + \dfrac{6}{5}\\ = – 8 + \dfrac{1}{3} + \dfrac{6}{5}\\ = \dfrac{{ – 8.15 + 5 + 18}}{{15}} = \dfrac{{ – 120 + 23}}{{15}} = – \dfrac{{97}}{{15}}\\ C2:8 – \dfrac{9}{4} + \dfrac{2}{7} + 6 + \dfrac{3}{7} – \dfrac{5}{4} – 3 – \dfrac{2}{4} + \dfrac{9}{7}\\ = \left( {8 + 6 – 3} \right) + \left( { – \dfrac{9}{4} – \dfrac{5}{4} – \dfrac{2}{4}} \right) + \left( {\dfrac{2}{7} + \dfrac{3}{7} + \dfrac{9}{7}} \right)\\ = 11 + \dfrac{{ – 9 – 5 – 2}}{4} + \dfrac{{14}}{7} = 11 – 4 + 2 = 9\\ C3:\\ – \dfrac{1}{2} + \dfrac{3}{5} – \dfrac{1}{9} + \dfrac{1}{{131}} + \dfrac{2}{7} + \dfrac{4}{{35}} – \dfrac{7}{{18}}\\ = \left( { – \dfrac{1}{2} – \dfrac{1}{9} – \dfrac{7}{{18}}} \right) + \left( {\dfrac{3}{5} + \dfrac{2}{7} + \dfrac{4}{{35}}} \right) + \dfrac{1}{{131}}\\ = \left( {\dfrac{{ – 9 – 2 – 7}}{{18}}} \right) + \left( {\dfrac{{21 + 10 + 4}}{{35}}} \right) + \dfrac{1}{{131}}\\ = – 1 + 1 + \dfrac{1}{{131}} = \dfrac{1}{{131}}\\ C4:\\ \dfrac{1}{3} – \dfrac{3}{4} + \dfrac{3}{5} + \dfrac{1}{{64}} – \dfrac{2}{9} – \dfrac{1}{{36}} + \dfrac{1}{{15}}\\ = \left( {\dfrac{1}{3} + \dfrac{3}{5} + \dfrac{1}{{15}}} \right) + \left( { – \dfrac{3}{4} – \dfrac{2}{9} – \dfrac{1}{{36}}} \right) + \dfrac{1}{{64}}\\ = \dfrac{{5 + 9 + 1}}{{15}} – \dfrac{{27 + 8 + 1}}{{36}} + \dfrac{1}{{64}}\\ = 1 – 1 + \dfrac{1}{{64}}\\ = \dfrac{1}{{64}}\\ C5:\\ \left( {\dfrac{1}{3} – \dfrac{1}{3}} \right) + \left( { – \dfrac{3}{5} + \dfrac{3}{5}} \right) + \left( {\dfrac{5}{7} – \dfrac{5}{7}} \right) + \left( { – \dfrac{7}{9} + \dfrac{7}{9}} \right) + \left( {\dfrac{9}{{11}} – \dfrac{9}{{11}}} \right) + \left( { – \dfrac{{11}}{{13}} + \dfrac{{11}}{{13}}} \right) + \dfrac{{13}}{{15}}\\ = \dfrac{{13}}{{15}} \end{array}$$

2. Giải thích các bước giải:

C1/ (3 – 1/4 + 2/3) – (5 + 1/3 – 6/5)-(6 – 7/4 + 3/2)

= 3 – 1/4 + 2/3 – 5 – 1/3 + 6/5 – 6 + 7/4 – 3/2

= (3 – 5 – 6) + (-1/4 + 7/4 – 3/2) + (2/3 – 1/3) + 6/5

= -8 + 1/3 + 6/5 = -97/15

C2/ (8 – 9/4 + 2/7)-(-6 – 3/7 + 5/4)-(3 + 2/4 – 9/7)

= 8 – 9/4 + 2/7 + 6 + 3/7 – 5/4 – 3 – 2/4 + 9/7

= (8 + 6-3) – (9/4 + 5/4 + 2/4) + (2/7 +3/7 +  9/7)

= 11 – 4 +2 = 9

C3/ (-1/2) – (-3/5) +(-1/9) + 1/131 – (-2/7) + 4/35 – 7/18

= -(1/2 + 1/9 + 7/18) + (3/5 + 2/7 + 4/35) + 1/131

= -1 + 1 + 1/131=1/131

C4/ 1/3 – 3/4 – (-3/5) + 1/64 – 2/9 – 1/36 + 1/15

= (1/3 + 3/5 + 1/15) -(3/4 + 2/9 + 1/36) + 1/64

=  1 – 1 + 1/64=1/64

C5/ 1/3 – 3/5 + 5/7 – 7/9 + 9/11 – 11/13 + 13/15 + 11/13 – 9/11 + 7/9 – 5/7 + 3/5 – 1/3

= (1/3 – 1/3)+(-3/5 + 3/5)+(5/7 – 5/7) + (-7/9 + 7/9) + (9/11 – 9/11) + (-11/13 + 11/13) + 13/15

= 13/15

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