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hiệu 2 số là:
2-1=1
nên y sẽ là 1
nên ta có tổng là:
37x37x2=2738
đáp số:2738
37 x y + 1 + 2 + 3+ ...+37 = 37 x y + (1 + 37) : 2 x 37
= 37 x (y + 19)
A= (x+x+x+....+x+x)+(1+2+3+4+...+37)=999
tìm số số hạng (37-1):1+1=37
tìm tổng 1+2+3+..+37=(37+1)x37:2=703
=>A=37x+703=999
=>37x=999-703=296
=>x=296:37=8
Vậy x=8
a){ x+1} +{x+2}+[x+3]+[x+4]+....+[x+37]=999
=>(x+x+...+x)+(1+2+3+...+37)=999
=>37x+703=999
=>37x=296
=>x=8
Bài 4:
\(\dfrac{3}{4}+y:\dfrac{2}{5}=\dfrac{37}{16}\)
\(\Rightarrow y:\dfrac{2}{5}=\dfrac{37}{16}-\dfrac{3}{4}\)
\(\Rightarrow y:\dfrac{2}{5}=\dfrac{25}{16}\)
\(\Rightarrow y=\dfrac{2}{5}\cdot\dfrac{25}{16}\)
\(\Rightarrow y=\dfrac{5}{8}\)
________________
\(456+y:87=23987\)
\(\Rightarrow y:87=23987-456\)
\(\Rightarrow y:87=23531\)
\(\Rightarrow y=23531\cdot87\)
\(\Rightarrow y=2047197\)
a)\(\dfrac{4}{5}\times\dfrac{5}{8}:\dfrac{4}{5}\)
\(=\left(\dfrac{4}{5}:\dfrac{4}{5}\right)\times\dfrac{5}{8}\)
\(=1\times\dfrac{5}{8}=\dfrac{5}{8}\)
b)\(\dfrac{5}{6}+\left(\dfrac{1}{2}:\dfrac{3}{2}+\dfrac{4}{5}\right)\)
\(=\dfrac{5}{6}+\left(\dfrac{1}{3}+\dfrac{4}{5}\right)\)
\(=\dfrac{5}{6}+\dfrac{17}{15}\)
\(=\dfrac{59}{30}\)
Bài 2:
a) \(\dfrac{3}{4}+y:\dfrac{2}{5}=\dfrac{37}{16}\)
\(y:\dfrac{2}{5}=\dfrac{37}{16}-\dfrac{3}{4}\)
\(y:\dfrac{2}{5}=\dfrac{25}{16}\)
\(y=\dfrac{25}{16}\times\dfrac{2}{5}\)
\(y=\dfrac{5}{8}\)
b)\(456+y:87=23987\)
\(y:87=23987-456\)
\(y:87=23531\)
\(y=23531\times87\)
\(y=2047197\)
a) \(y+2\frac{1}{3}=3\)
=> y + 7/3 = 3
=> y = 3 - 7/3
=> y = 2/3
b) \(y-1\frac{1}{4}=1\frac{1}{8}\)
=> y - 5/4 = 9/8
=> y = 9/8 + 5/4
=> y = 19/8
c) \(3-y=1\frac{1}{4}\)
=> 3 - y = 5/4
=> y = 3 - 5/4
=> y = 7/4
d) \(y\times2\frac{3}{5}=1\frac{13}{15}\)
=> y x 13/5 = 28/15
=> y = 28/15 : 13/5
=> y = 28/39
e) \(2:y=2\frac{3}{7}\)
=> 3 : y = 17/7
=> y = 3 : 17/7
=> y = 21/17
a) y + 2/1/3 = 3
y + 7/3 = 3
y = 2/3
cac bai con lai bn tu dua vao cong thuc da hoc mak lm nha!
\(y+y.\frac{1}{3}.\frac{9}{2}+y.\frac{7}{2}=25\)
\(y+y.6+y.\frac{7}{2}=25\)
\(y.\left(1+6+\frac{7}{2}\right)=25\)
\(y.\frac{21}{2}=25\)
\(y=25:\frac{21}{2}\)
\(y=25.\frac{2}{21}\)
\(y=\frac{50}{21}\)
\(y.5+y.3+y+y=50\)
\(y.\left(5+3+1+1\right)=50\)
\(y.10=50\)
\(y=5\)
( y+1) + ( y+2) + (y+3) + ( y+4)+...+( y+100) = 5750
=>( 100 x y )+ ( 1+2+3+4+ ...+ 100) = 5750
100 x y +[ (1+100) .100 : 2 ]= 5750
100 x y + 5050 = 5750
100 x y = 5750 - 5050
100 x y = 700
y = 700 : 100
y = 7
(y+1) +(y+2) + (y+3) + ( y+4) + ...+ (y+100)= 5750
............................
y=7
Hk tốt
a) \(\frac{37-2\times\left(y-3,25\right)}{5}=7,06\)
=> \(37-2\times\left(y-3,25\right)=7,06\times5\)
=> \(37-2\times\left(y-3,25\right)=35,3\)
=> \(2\times\left(y-3,25\right)=37-35,3=1,7\)
=> \(y-3,25=1,7:2=0,85\)
=> y = 0,85 + 3,25 = 4,1
Tới khúc này là dẫn đến tìm x chứ không tìm y nx ...
Sửa câu b lại đi
c) \(\frac{5}{12}\times\left(8+x\right)-\frac{1}{5}\times\left(\frac{15}{4}+x\right)=15\)
=> \(\frac{10}{3}+\frac{5}{12}x-\frac{3}{4}+\frac{1}{5}x=15\)
=> \(\left(\frac{10}{3}-\frac{3}{4}\right)-\left(\frac{5}{12}x-\frac{1}{5}x\right)=15\)
=> \(\frac{31}{12}+\frac{13}{60}x=15\)
=> \(\frac{13}{60}x=15-\frac{31}{12}=\frac{149}{12}\)
=> \(x=\frac{149}{12}:\frac{13}{60}=\frac{149}{12}\cdot\frac{60}{13}=\frac{745}{13}\)
Làm nốt câu d nhé
Tìm y giúp
\(\left(y+1\right)+\left(y+2\right)+\left(y+3\right)+\left(y+4\right)+...+\left(y+37\right)=999\)
\(y+y+y+y+...+y+1+2+3+4+...+37=999\) ( 37 số y )
Phần 1 + 2 + 3 + 4 + ... + 37 có : ( 37 - 1 ) / 1 + 1 = 37 ( số hạng )
\(\Rightarrow37y+\frac{\left(37+1\right)37}{2}=999\)
\(37y+703=999\)
\(37y=999-703\)
\(37y=296\)
\(y=\frac{296}{37}=8\)