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\(\Leftrightarrow\)\(\left(\frac{2}{3}+\frac{x}{5}\right)\)\(\times30-26=54\)
\(\Leftrightarrow20+6x\)\(-26=54\)
\(\Leftrightarrow6x=54+26-20\)
\(\Leftrightarrow6x=60\)
\(\Leftrightarrow x=10\)
Học tốt!
\(\left(\frac{4}{5}:\frac{6}{5}+\frac{1}{5}:\frac{1}{x}\right)\cdot30-26=54\)
\(\left(\frac{4}{5}\cdot\frac{5}{6}+\frac{1}{5}\cdot x\right)\cdot30=54+26\)
\(\left(\frac{2}{3}+\frac{x}{5}\right)\cdot30=80\)
\(\frac{2}{3}+\frac{x}{5}=80:30\)
\(\frac{2}{3}+\frac{x}{5}=\frac{8}{3}\)
\(\frac{x}{5}=\frac{8}{3}-\frac{2}{3}\)
\(\frac{x}{5}=2\)
\(x=10\)
a) 72 + 9 + 8 = ( 72 + 8 ) + 9
= 80 + 9
= 89
b)37 + 18 + 3 = ( 37 + 3 ) + 18
= 40 + 18
= 58
c) 48 + 26 + 4 = 48 + (26 + 4)
= 48 + 30
= 78
d)85 + 99 + 1 = 85 + ( 99 + 1 )
= 85 + 100 = 185
e) 67 + 98 + 33 = ( 67 + 33 ) + 98
= 100 + 98 = 198
a: 2/3+3/4=11/12
9/4+3/5=45/20+12/20=57/20
2/5+4/7=14/35+20/35=34/34
3/5+4/3=9/15+20/15=29/15
b: 3/12+1/4=2/4=1/2
4/25+3/5=4/25+15/25=19/25
26/81+4/27=26/81+12/81=38/81
5/64+7/8=5/64+56/64=61/64
Số số hạng trên dãy số trên là:
(26 - 1) : 1 +1 =26 (số)
tổng dãy số trên là:
(26 + 1) . 26 : 2= 351
Vậy tổng dãy số trên là : 351
1+2+3+4+5+......+25+26
=(1+26)+(2+25)+(3+24)+......+(13+14)
=27+27+27+......+27 (13 cặp)
=\(27\times13=351\)
\(1,\\ c,\dfrac{17}{6}-\dfrac{3}{7}-\dfrac{5}{6}=\dfrac{17\times7-3\times6-5\times7}{6\times7}=\dfrac{119-18-35}{42}=\dfrac{66}{42}=\dfrac{11}{7}\\ 2,\\ a,\dfrac{6}{9}+\dfrac{3}{15}+\dfrac{7}{15}\\ =\dfrac{6:3}{9:3}+\dfrac{7+3}{15}\\ =\dfrac{2}{3}+\dfrac{10}{15}\\ =\dfrac{2}{3}+\dfrac{2}{3}\\ =\dfrac{2+2}{3}=\dfrac{4}{3}\)
\(b,\dfrac{7}{2}+\dfrac{29}{12}-\dfrac{11}{12}\\ =\dfrac{7}{2}+\left(\dfrac{29}{12}-\dfrac{11}{12}\right)\\ =\dfrac{7}{2}+\dfrac{29-11}{12}\\ =\dfrac{7}{2}+\dfrac{18}{12}\\ =\dfrac{7}{2}+\dfrac{18:6}{12:6}\\ =\dfrac{7}{2}+\dfrac{3}{2}\\ =\dfrac{7+3}{2}=\dfrac{10}{2}=5\)
\(c,\dfrac{26}{25}-\dfrac{3}{5}-\dfrac{2}{5}\\ =\dfrac{26}{25}-\dfrac{3\times5}{5\times5}-\dfrac{2\times5}{5\times5}\\ =\dfrac{26-15-10}{25}\\ =\dfrac{1}{25}\)
Bài 1:
\(\dfrac{17}{6}-\dfrac{3}{7}-\dfrac{5}{6}=\left(\dfrac{17}{6}-\dfrac{5}{6}\right)-\dfrac{3}{7}=2-\dfrac{3}{7}=\dfrac{14}{7}-\dfrac{3}{7}=\dfrac{11}{7}\)
Bài 2:
a/\(\dfrac{6}{9}+\dfrac{3}{15}+\dfrac{7}{15}\)
\(=\dfrac{2}{3}+\left(\dfrac{3}{15}+\dfrac{7}{15}\right)\)
\(=\dfrac{2}{3}+\dfrac{2}{3}\)
\(=\dfrac{4}{3}\)
b/\(\dfrac{7}{2}+\dfrac{29}{12}-\dfrac{11}{12}\)
\(=\dfrac{7}{2}+\left(\dfrac{29}{12}-\dfrac{11}{12}\right)\)
\(=\dfrac{7}{2}+\dfrac{3}{2}\)
\(=5\)
c/\(\dfrac{26}{25}-\dfrac{3}{5}-\dfrac{2}{5}\)
\(=\dfrac{26}{25}-\left(\dfrac{3}{5}+\dfrac{2}{5}\right)\)
\(=\dfrac{26}{25}-1\)
\(=\dfrac{26}{25}-\dfrac{25}{25}\)
\(=\dfrac{1}{25}\)
#Đang Bận Thở
Bài 1
245+368+155+332/25.4
=(245+155)+(368+332)/100
=400+700/100
=1100/100
=11/1=11
Bài 2
X:6+234578=20208+197356+39792+202644
X:6+234578=(20208+39792)+(197356+202644)
X:6+234578=60000+400000=460000 (bước này mk rút gọn cho dễ, nhưng trong tập thì bạn có thể làm ra từng bước nha)
X:6=460000-234578
X:6=225422
X =225422.6
X =1 352 532.
Tính nhanh
19 + 18 + 17 + 16 + 14 + 21 + 22 + 23 + 24 + 25 + 26
1/3 + 1/4 + 1/5 + 4/6 + 9/12 + 16/20
\(19+18+17+16+14+21+22+23+24+25+26\)
\(=\left(19+21\right)+\left(18+22\right)+\left(17+23\right)+\left(16+24\right)+\left(14+26\right)+25\)
\(=30+30+30+30+30+25\)
\(=175\)
\(\dfrac{1}{3}+\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{4}{6}+\dfrac{9}{12}+\dfrac{16}{20}\)
\(=\dfrac{1}{3}+\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{2}{3}+\dfrac{3}{4}+\dfrac{4}{5}\)
\(=\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\left(\dfrac{1}{4}+\dfrac{3}{4}\right)+\left(\dfrac{1}{5}+\dfrac{4}{5}\right)\)
\(\text{=}1+1+1\)
\(\text{=}3\)
15x3/5=9
4/2x1/2=1
6/25x5/8=3/20
15:1/3=45
35:1/5=175
4/5:1/2=8/5
k mk nha.
\(15\times\frac{3}{5}=\frac{45}{5}=9\)
\(\frac{4}{2}\times\frac{1}{2}=\frac{4}{4}=1\)
\(\frac{6}{25}\times\frac{5}{8}=\frac{30}{200}=\frac{3}{20}\)
\(15:\frac{1}{3}=\frac{45}{1}=45\)
\(35:\frac{1}{5}=\frac{175}{1}\)
\(\frac{4}{5}:\frac{1}{2}=\frac{8}{5}\)
\(\frac{6}{25}:\frac{5}{8}=\frac{48}{125}\)