63/61 +56/97- 2/61 -56/97
giải giúp mình nha mình đang cần gấp
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\(3\times x+56=2\times x+61\)
\(\Rightarrow3x+56=2x+61\)
\(\Rightarrow3x-2x=61-56\)
\(\Rightarrow1x=5\)
\(\frac{1}{3}+\frac{13}{15}+\frac{33}{35}+\frac{61}{63}+\frac{97}{99}+\frac{141}{143}\)
\(=\left(1-\frac{2}{3}\right)+\left(1-\frac{2}{15}\right)+\left(1-\frac{2}{35}\right)+\left(1-\frac{2}{63}\right)+\left(1-\frac{2}{99}\right)+\left(1-\frac{2}{143}\right)\)
\(=\left(1+1+1+1+1+1\right)-\left(\frac{2}{3}+\frac{2}{15}+\frac{2}{35}+\frac{2}{63}+\frac{2}{99}+\frac{2}{143}\right)\)
\(=6-\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}+\frac{2}{11.13}\right)\)
\(=6-\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+\frac{1}{11}-\frac{1}{13}\right)\)
\(=6-\left(1-\frac{1}{13}\right)\)
\(=6-\frac{12}{13}\)
\(=\frac{66}{13}\)
Ủng hộ mk nha ^_-
5/2+13/6+25/12+41/20+61/30+85/42
=2+1/2+2+1/6+2+1/12+2+1/20+2+1/30+2+1/42
=12+(1/2+1/6+1/12+1/20+1/30+1/42)
=12+(1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6.7)
=12+(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7)
=12+1-1/7
=90/7
S = 3/3.5 + 3/7.9 +3/9.11 +...+ 3/59.61
S = 3/2 . (2/5.7 + 2/7.9 + 2/9.11 + ... + 2/59.61)
S = 3/2 . (1/5 - 1/7 + 1/7 - 1/9 + 1/9 - 1/11 + ... +1/59 - 1/61)
S = 3/2 . (1/5 - 1/61)
S = 3/2 . 56/305
S = 84/305
VẬY ĐÁP ÁN LÀ B NHA
18 * 23 +3 +45 * 6 +9 * 32 *2 =1263
425 *7*4 - 170 *60=1700
132 *9 +132 =1320
( 56* 27 +56 +35 ):62=\(\frac{1603}{62}\)
39 * ( 250 +87) +61 * ( 240 +97)=33700
Hk tốt!!! k cho mình nha!!@@
= \(\left(\frac{63}{61}-\frac{2}{61}\right)\)+ \(\left(\frac{56}{97}-\frac{56}{97}\right)\)
= 1 + 0
= 1