1+3+5+7+...+x=3775
Tìm x
(x+1)+(2x+3)+(3x+5)+...+(50x+99)=3775
(x+1)+(2x+3)+(3x+5)+...+(50x+99)=3775
=> (x + 2x + 3x + ... + 50x) + (1 + 3 + 5 + ... + 99) = 3775
=> x . (1 + 2 +3 + ...+ 50) + (1 + 3 + 5 + ... + 99) = 3775
Áp dụng công thức tính dãy số ta có :
\(1+2+3+...+50=\frac{\left[\left(50-1\right):1+1\right].\left(50+1\right)}{2}=\frac{50.51}{2}=25.51=1275\)
\(1+3+5+...+99=\frac{\left[\left(99-1\right):2+1\right].\left(99+1\right)}{2}=\frac{50.100}{2}=50.50=2500\)
=> x . 1275 + 2500 = 3775
=> 1275x = 1275
=> x = 1
Câu 1 : tính nhanh a) 7/13 * 7/15 - 5/12 * 21/39+ 49/91 * 8/15
b) ( 12/199 + 23/200 - 34/201 ) * ( 1/2 -1/3 -1/6 )
Câu 2 : So sánh
a) 7150và 3775
b) 10750 và 7375
Câu 3 : Tìm số tự nhiên có 2 chữ số , biết rằng nếu nhân nó với 135 thì ta đc một số chính phương
B2: tìmX
A.13 x X+ 14 x X=50
B. ( X+2) +( X+4) +…+ (X+ 100)=3550
C.(1- X)+(2- X)+ (3- X)+…+ (100- X)=50
D. ( X+1)+(2x X+3)+(3 x X+5)+…+(50 x X +99)= 3775
K. 5 x X-(1+2+3+…+30)=135
M. X- 165
+ 546= 562
X
A. \(13x+14x=50\)
\(\Leftrightarrow17x=50\)
\(\Leftrightarrow x=\frac{50}{17}\)
a) 13x+14x = 50
=> x.(13+14)=50
x+27=50
x = 50-27
x=23 ( bài này ko chắc lắm )
b) (x+2)+(x+4)+...+(x+100)=3550
=> có 50 cặp như vậy
(x+x+x+...+x)+(2+4+...+100)=3550
<=>50x+2550=3550
50x=3550-2550
50x=1000
x=1000:50
x=20
c) (1-x)+(2-x)+...+(100-x)=50
=> có 100 như vậy
(1+2+3+...+100)-(x+x+x+...+x)=50
<=>5050-100x=50
100x=5050-50
100x=5000
x=5000:100
x=50
d) để mình nghĩ cách làm lại đã rồi mình sẽ trả lời lại sau
k) 5x-(1+2+3+...+30)=135
5x-465=135
5x=135+465
5x=600
x=600:5
x=120
m) \(\frac{x-165}{x}\)+546=562
\(\frac{x-165}{x}\)=562-546
\(\frac{x-165}{x}\)=16
\(\Rightarrow\frac{x-165}{x}=\frac{16}{1}\)
<=> x-165=16
x=16+165
x=181 ( ko chắc )
d) (1x+1)+(2x+3)+(3x+5)+...+(50x+99)=3775
<=> (1x+2x+3x+...+50x)+(1+3+5+...+99)=3775
=> (1x+2x+3x+...+50x)+2500=3775
=> (1x+2x+3x+...+50x)=3775-2500
=> (1x+2x+3x+...+50x)=1275
<=> [x(1+2+3+...+50)]=1275
=> x.1275=1275
x=1275:1275
x=1
So Sánh : 7150 và 3775
Có: \(71^{50}=\left(71^2\right)^{25};37^{75}=\left(37^3\right)^{25}\)
Lại có: \(71^2< 72^2=\left(2\cdot36\right)^2=2^2\cdot36^2=4\cdot36^2< 36\cdot36^2=36^3< 37^3\)
Vậy \(71^{50}< 37^{75}\)
Ta có: \(71^{50}=\left(71^2\right)^{25}=5041^{25}\)
\(37^{75}=\left(37^3\right)^{25}=50653^{25}\)
mà \(5041^{25}< 50653^{25}\)
nên \(71^{50}< 37^{75}\)
TRung bình mỗi con gà mái đẻ trứng ăm hết 104g thức ăn trong 1 ngày . Hỏi trại chăn nuôi đó cần bao nhiêu kg thức ăn cho 3775 con gà mái đẻ ăn trong 10 ngày
cả lời giải cả phép tính
1 Con ga mai an het trong 10 ngay la :
104 . 10 = 1040 (g)
3775 con ga mai an het trong 10 ngay la :
1040 . 3775=3926000 (g)
Doi : 3926000(g)=3926(kg)
DS: 3926 kg
**** nhe
1/ x + 1/2 = -5/3 6/ x - 1/5 = 9/10
2/ 1/3 - x = 3/5 7/ x + 5/12 = 3/8
3/ 3-4 + x = 7/2 8/ x + 5/4 = 7/6
4/ x - 4/3 = -7/9 9/ x - 2/7 = 1/35
5/ x - -7/3 = 5/6 10/ x - 1/5 = -7/10
\(1,\\ x+\dfrac{1}{2}=-\dfrac{5}{3}\\ x=-\dfrac{5}{3}-\dfrac{1}{2}\\ x=-\dfrac{13}{6}\\ Vậyx=-\dfrac{13}{6}\)
\(2,\\ \dfrac{1}{3}-x=\dfrac{3}{5}\\ x=\dfrac{1}{3}-\dfrac{3}{5}\\ x=-\dfrac{4}{15}\\ Vậyx=-\dfrac{4}{15}\)
\(3,\\ 3-4+x=\dfrac{7}{2}\\ -1+x=\dfrac{7}{2}\\ x=\dfrac{7}{2}+1\\ x=\dfrac{9}{2}\\ Vậyx=\dfrac{9}{2}\)
\(4,\\ x-\dfrac{4}{3}=-\dfrac{7}{9}\\ x=-\dfrac{7}{9}+\dfrac{4}{3}\\ x=\dfrac{15}{27}\\ Vậyx=\dfrac{15}{27}\)
\(5,\\ x-\left(-\dfrac{7}{3}\right)=\dfrac{5}{6}\\ x=\dfrac{5}{6}-\dfrac{7}{3}\\ x=-\dfrac{27}{18}\\ Vậyx=-\dfrac{27}{18}\)
\(6,\\ x-\dfrac{1}{5}=\dfrac{9}{10}\\ x=\dfrac{9}{10}+\dfrac{1}{5}\\ x=\dfrac{11}{10}\\ Vậyx=\dfrac{11}{10}\)
\(7,\\ x+\dfrac{5}{12}=\dfrac{3}{8}\\ x=\dfrac{3}{8}-\dfrac{5}{12}\\ x=-\dfrac{1}{24}\\ Vậyx=-\dfrac{1}{24}\)
\(8,\\ x+\dfrac{5}{4}=\dfrac{7}{6}\\ x=\dfrac{7}{6}-\dfrac{5}{4}\\ x=-\dfrac{9}{24}\\ Vậyx=-\dfrac{9}{24}\)
\(9,\\ x-\dfrac{2}{7}=\dfrac{1}{35}\\ x=\dfrac{1}{35}+\dfrac{2}{7}\\ x=\dfrac{11}{35}\\ Vậyx=\dfrac{11}{35}\\ 10,\\ x-\dfrac{1}{5}=-\dfrac{7}{10}\\ x=-\dfrac{7}{10}+\dfrac{1}{5}\\ x=-\dfrac{1}{2}\\ Vậyx=-\dfrac{1}{2}\)
ahiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii hãy ấn a
1) x+1/2=-5/3
2) 1/3-x=3/5
4) x-4/3=-7/9
5) x--7/3=5/6
6) x-1/5=9/10
7) x+5/12=3/8
8) x+5/4=7/6
9) x-2/7=1/35
10) x-2/7=-7/10
6: =>x=9/10+1/5=9/10+2/10=11/10
7: =>x=3/8-5/12=36/96-40/96=-1/24
8: =>x=7/6-5/4=14/12-15/12=-1/12
9: =>x=1/35+2/7=1/35+10/35=11/35
10: =>x=2/7-7/10=20/70-49/70=-29/70
1, \(x=-\dfrac{5}{3}-\dfrac{1}{2}=-\dfrac{10}{6}-\dfrac{3}{6}=-\dfrac{13}{6}\)
2, \(x=\dfrac{1}{3}-\dfrac{3}{5}=\dfrac{5-9}{15}=-\dfrac{4}{15}\)
4, \(x=-\dfrac{7}{9}+\dfrac{4}{3}=\dfrac{-7+12}{9}=\dfrac{5}{9}\)
5, \(x=\dfrac{5}{6}-\dfrac{7}{3}=\dfrac{5-14}{6}=-\dfrac{9}{6}=-\dfrac{3}{2}\)
6, \(x=\dfrac{9}{10}+\dfrac{1}{5}=\dfrac{9+2}{10}=\dfrac{11}{10}\)
7, \(x=\dfrac{3}{8}-\dfrac{5}{12}=\dfrac{9-10}{12}=-\dfrac{1}{12}\)
8, \(x=\dfrac{7}{6}-\dfrac{5}{4}=\dfrac{14-15}{12}=-\dfrac{1}{12}\)
9, \(x=\dfrac{1}{35}+\dfrac{2}{7}=\dfrac{1+10}{35}=\dfrac{11}{35}\)
10, \(x=-\dfrac{7}{10}+\dfrac{2}{7}=\dfrac{-49+20}{70}=\dfrac{-29}{70}\)
1) x+1/2=-5/3
2) 1/3-x=3/5
4) x-4/3=-7/9
5) x--7/3=5/6
6) x-1/5=9/10
7) x+5/12=3/8
8) 5/4=7/6
9) x-2/7=1/35
10) x-2/7=-7/10
cả phép tính nữa nha
1: =>x=-5/3-1/2=-13/6
2: =>x=1/3-3/5=-4/15
4: =>x=-7/9+4/3=-7/9+12/9=5/9
5: =>x=5/6-7/3=5/6-14/6=-9/6=-3/2
6: =>x=9/10+1/5=11/10
7: =>x=3/8-5/12=36/96-40/96=-1/24
8: Đề sai rồi bạn
1/ x + 1/2 = -5/3
2/ 1/3 - x = 3/5
3/ 3-4 + x = 7/2
4/ x - 4/3 = -7/9
5/ x - -7/3 = 5/6
6/ x - 1/5 = 9/10
7/ x + 5/12 = 3/8
8/ x + 5/4 = 7/6
9/ x - 2/7 = 1/35
10/ x - 1/5 = -7/10
1/ \(x+\dfrac{1}{2}=\dfrac{-5}{3}\)
\(x=\dfrac{-5}{3}-\dfrac{1}{2}\)
\(x=\dfrac{-10}{6}-\dfrac{3}{6}\)
Vậy \(x=\dfrac{-13}{6}\)
2/\(\dfrac{1}{3}-x=\dfrac{3}{5}\)
\(-x=\dfrac{3}{5}-\dfrac{1}{3}\)
\(-x=\dfrac{9}{15}-\dfrac{5}{15}\)
\(-x=\dfrac{4}{15}\)
Vậy \(x=\dfrac{-4}{15}\)
3/ \(3-4+x=\dfrac{7}{2}\)
\(-4+x=\dfrac{7}{2}-3\)
\(-4+x=\dfrac{7}{2}-\dfrac{6}{2}\)
\(-4+x=\dfrac{1}{2}\)
\(x=\dfrac{1}{2}+4\)
\(x=\dfrac{1}{2}+\dfrac{8}{2}\)
Vậy \(x=\dfrac{9}{2}\)
4/ \(x-\dfrac{4}{3}=\dfrac{-7}{9}\)
\(x=\dfrac{-7}{9}+\dfrac{4}{3}\)
\(x=\dfrac{-7}{9}+\dfrac{12}{9}\)
Vậy \(x=\dfrac{5}{9}\)
5/ \(x-\dfrac{-7}{2}=\dfrac{5}{6}\)
\(x=\dfrac{5}{6}-\dfrac{7}{2}\)
\(x=\dfrac{5}{6}-\dfrac{21}{6}\)
Vậy \(x=\dfrac{-16}{6}=\dfrac{-8}{3}\)
6/ \(x-\dfrac{1}{5}=\dfrac{9}{10}\)
\(x=\dfrac{9}{10}+\dfrac{1}{5}\)
\(x=\dfrac{9}{10}+\dfrac{2}{10}\)
Vậy \(x=\dfrac{11}{10}\)
7/ \(x+\dfrac{5}{12}=\dfrac{3}{8}\)
\(x=\dfrac{3}{8}-\dfrac{5}{12}\)
\(x=\dfrac{9}{24}-\dfrac{10}{24}\)
Vậy \(x=\dfrac{-1}{24}\)
8/ \(x+\dfrac{5}{4}=\dfrac{7}{6}\)
\(x=\dfrac{7}{6}-\dfrac{5}{4}\)
\(x=\dfrac{14}{12}-\dfrac{15}{12}\)
Vậy \(x=\dfrac{-1}{12}\)
9/ \(x-\dfrac{2}{7}=\dfrac{1}{35}\)
\(x=\dfrac{1}{35}+\dfrac{2}{7}\)
\(x=\dfrac{1}{35}+\dfrac{10}{35}\)
Vậy \(x=\dfrac{11}{35}\)
10 /\(x-\dfrac{1}{5}=\dfrac{-7}{10}\)
\(x=\dfrac{-7}{10}+\dfrac{1}{5}\)
\(x=\dfrac{-7}{10}+\dfrac{2}{10}\)
Vậy \(x=\dfrac{-5}{10}=\dfrac{-1}{2}\)