x+1\15+x+2\16+x+3\17
x+1\15+x+2\16+x+3\17=3
Ta có: \(\frac{x+1}{15}+\frac{x+2}{16}+\frac{x+3}{17}=3\)
=> \(\left(\frac{x+1}{15}-1\right)+\left(\frac{x+2}{16}-1\right)+\left(\frac{x+3}{17}-1\right)=0\)
=> \(\frac{x-14}{15}+\frac{x-14}{16}+\frac{x-14}{17}=0\)
=> \(\left(x-14\right)\left(\frac{1}{15}+\frac{1}{16}+\frac{1}{17}\right)=0\)
=> \(x-14=0\)
=> \(x=14\)
x+1\15+x+2\16+x+3\17=0
x+1/18 + x+2/17 = x+3/16 + x+4/15
\(\frac{x+1}{18}+\frac{x+2}{17}=\frac{x+3}{16}+\frac{x+4}{15}\)
\(\Rightarrow\frac{x+1}{18}+1+\frac{x+2}{17}+1=\frac{x+3}{16}+1+\frac{x+4}{15}+1\)
\(\Rightarrow\frac{x+19}{18}+\frac{x+19}{17}-\frac{x+19}{16}-\frac{x+19}{15}=0\)
\(\Rightarrow\left(x+19\right).\left(\frac{1}{18}+\frac{1}{17}-\frac{1}{16}-\frac{1}{15}\right)=0\)
Vì \(\frac{1}{18}+\frac{1}{17}-\frac{1}{16}-\frac{1}{15}\ne0\)
Nên \(x+19=0\)
\(\Rightarrow x=-19\)
Vậy x = -19
a,100-99+98-97+96-95...+6-5+4-3+2-1
b, Hiệu (1 x 2 x 3 x ... x 15 x 16 x 17 x 18 x 19)-( 1 x 3 x 5 x ... x 15 x 17 x 19) tận cùng bằng chữ số gì ?
b)Tận cùng=5 hoặc 0 nhưng mình ngại viết lắm,thông cảm nha
1 x 2 x 3 x 4 x 5 x 6 x 7 x ( 4 x 8 - 16 x 2 ) x 15 x 16 x 17 ... x 2019 x 2020
Tính ngoặc tròn
\(4\cdot8-16\cdot2\)
\(=32-32\)
\(=0\)
Vậy tích trên bằng 0 ( vì có 1 thừa số = 0 )
Bài giải
1 x 2 x 3 x 4 x 5 x 6 x 7 x ( 4 x 8 - 16 x 2 ) x 15 x 16 x 17 ... x 2019 x 2020
= 1 x 2 x 3 x 4 x 5 x 6 x 7 x ( 32 - 32 ) x 15 x 16 x 17 ... x 2019 x 2020
= 1 x 2 x 3 x 4 x 5 x 6 x 7 x 0 x 15 x 16 x 17 ... x 2019 x 2020
= 0
chắt do tui quên tính 4 x 8 - 16 x 2 nên mới vậy :v
Tìm x biết
x+1/17+x+2/16=x+3/15+x+4/14
Tìm số nguyên x, biết:
1) -16 + 23 + x = - 16
2) 2x – 35 = 15
3) 3x + 17 = 12
4) (2x – 5) + 17 = 6
5) 10 – 2(4 – 3x) = -4
6) - 12 + 3(-x + 7) = -18
Tìm số nguyên x, biết:
1) -16 + 23 + x = - 16
7+x=-16
x=-16-7
x=-23
2) 2x – 35 = 15
2x=15+35
2x=50
x=50:2
x=25
3) 3x + 17 = 12
3x=12-17
3x=-5
x=-5/3
4) (2x – 5) + 17 = 6
2x-5=6-17
2x-5=-11
2x=-11+5
2x=-6
x=-6:2
x=-3
5) 10 – 2(4 – 3x) = -4
2(4-3x)=10-(-4)
2(4-3x)=14
4-3x=14:2
4-3x=7
3x=4-7
3x=-3
x=-3:3
x=-1
6) - 12 + 3(-x + 7) = -18
3(-x+7)=-18-(-12)
3(x+7)=-6
x+7=-6:3
x+7=-2
x=-2-7
x=-9
tự đi mà làm
1,Tính giá trị biểu thức
a, 13 . 17 - 256 : 16 + 14 : 7 - 1
b, 15 . 24 - 14 . 5 . (145 : 5 - 27)
c, 15 . 8 - (17 - 30 + 83) - 144 : 6
d,18 - 4 . (27 - 90 + 73) : 10
2,Tìm x
a, 315 - (135 - x)=215
b, x - 320 : 32 = 25 . 16
c, 3 . x - 2018 : 2 = 23
d, 280 - 9 . x - x = 80
e, 38 . x - 12 . x - x . 16 = 40
Giúp mình với nhé,mình đang cần gấp !!
2,
a) \(315-\left(135-x\right)=215\)
\(\Rightarrow135-x=315-215\)
\(\Rightarrow135-x=100\)
\(\Rightarrow x=135-100\)
\(\Rightarrow x=35\)
b) \(x-320:32=25\cdot16\)
\(\Rightarrow x-10=5^2\cdot4^2\)
\(\Rightarrow x-10=20^2\)
\(\Rightarrow x-10=400\)
\(\Rightarrow x=410\)
c) \(3\cdot x-2018:2=23\)
\(=3\cdot x-1009=23\)
\(\Rightarrow3\cdot x=1032\)
\(\Rightarrow x=1032:3\)
\(\Rightarrow x=344\)
d) \(280-9\cdot x-x=80\)
\(\Rightarrow280-x\cdot\left(9+1\right)=80\)
\(\Rightarrow280-10\cdot x=80\)
\(\Rightarrow10\cdot x=280-80\)
\(\Rightarrow10\cdot x=200\)
\(\Rightarrow x=20\)
e) \(38\cdot x-12\cdot x-x\cdot16=40\)
\(\Rightarrow x\cdot\left(38-12-16\right)=40\)
\(\Rightarrow x\cdot10=40\)
\(\Rightarrow x=40:10\)
\(\Rightarrow x=4\)
Tìm x nha
Giấu《 là dấu < hoặc bằng
1)-8/3+-1/3<x<-2/7+-5/7
2)8/17+5/17<×/17<10/17+5/17
8)-5/6+8/3+-29/6《x《-1/2+2+5/2
9)-8/11+2/11+13/11《x《8/15+9/15-2/15+2
7)×/5=-5/16+3/4-1/2