1/9 + 2x = 37/9
a)Cho số abc chia hết cho 37. Chứng minh rằng số cab cũng chia hết cho 37
b)tìm x:
1+3+5+7+9+...+(2x-1)=225
a)Ta có: abc\(⋮\)37 => 100.abc \(⋮\)37 => abc00 \(⋮\)37
=> (ab.1000 + c00) \(⋮\)37
=>[ab.999 + ( c00 + ab) ] \(⋮\)37
=>( ab . 99 + cab) \(⋮\)37
mà ab.999 = ab .27 .37 \(⋮\)37
=> cab \(⋮\)37
Vậy nếu abc \(⋮\)37 thì cab \(⋮\)37
b)1+3+5+7+9+...+(2x-1)=225
Với mọi x \(\in\)N, ta có 2x - 1 là số lẻ
Ta đặt A = 1 + 3 + 5 + 7 + 9+...+ (2x-1)=225
=> A là tổng của các số lẻ liên tiếp từ 1 đến (2x -1)
Số số hạng của A là:
[(2x - 1 - 1) : 2 + 1 = x (số hạng)
=> A= [(2x - 1) + 1] . x : 2 = x2
Mà A= 225 => x 2 = 225 = 152
\(\Rightarrow x=15\)
1.(-86-x)-(3+2x)=-4-15
2.18+(-x)-(40-28)=-32-(-18)
3.-27-(-31+x)-25=-5-17
4.-9-14-x+42)-38=-5+13
45-(-x+1)+50=2x-5+37
1) Ta có: \(\left(-86-x\right)-\left(3+2x\right)=-4-15\)
\(\Leftrightarrow-86-x-3-2x+4+15=0\)
\(\Leftrightarrow-3x-70=0\)
\(\Leftrightarrow-3x=70\)
hay \(x=-\dfrac{70}{3}\)
Vậy: \(x=-\dfrac{70}{3}\)
2) Ta có: \(18+\left(-x\right)-\left(40-28\right)=-32-\left(-18\right)\)
\(\Leftrightarrow18-x-40+28+32-18=0\)
\(\Leftrightarrow-x+20=0\)
\(\Leftrightarrow-x=-20\)
hay x=20
Vậy: x=20
3) Ta có: \(-27-\left(-31+x\right)-25=-5-17\)
\(\Leftrightarrow-27+31-x-25+5+17=0\)
\(\Leftrightarrow-x+1=0\)
\(\Leftrightarrow-x=-1\)
hay x=1
Vậy: x=1
4) Ta có: \(-9-14-x+42-38=-5+13\)
\(\Leftrightarrow-x-19=8\)
\(\Leftrightarrow-x=27\)
hay x=-27
Vậy: x=-27
B) 17X - ( -16X - 37 ) + 2x + 43
C) -2x -3.( x-17) = 34 -2 (-2x +25)
D) 17x+ 3. ( -16x -37) = 2x +43 -4x
E) {- 3x +2. [45 - x-3 (3x + 7) - 2x] + 4x} =55
F) -103 - 57 : [ -2 ( 2x -1 )2 - ( -9 )0 ] - 106
G) -2x + 3. { 12-2 [ 3x - ( 20 + 2x ) - 4x ] + 1} = 45
37+(13-│2x+7│)=6^30:(9^14.4^15)
-2x – (x – 17) = 34 – (-x + 25)
17x – ( -16x – 37) = 2x + 43
-2x –3. (x – 17) = 34 – 2(-x + 25)
17x + 3. ( -16x – 37) = 2x + 43 - 4x
{ -3x + 2.[ 45- x -3( 3x+ 7 -2x ] +4x } = 55
103 -57: [-2. (2x – 1 ) ^ 2 – (-9) ^ 0 ] = -106
1)-2x – (x – 17) = 34 – (-x + 25)
-2x-x-_17
x+2/13+2x+45/15=3x+8/37+4x+69/9
Tìm x : a) |9-7x| = 5x-3
b) 8x - | 4x +1 | = x+2
c) | 17x - 5 | - | 17x + 5 | = 0
d) | 3x +4 | = 2 | 2x - 9 |
e) | 10x + 7 | < 37
f) |3-8x| ≤19
g) | x + 3 | - 2x = | x-4 |
a: =>|7x-9|=5x-3
\(\Leftrightarrow\left\{{}\begin{matrix}x>=\dfrac{3}{5}\\\left(7x-9-5x+3\right)\left(7x-9+5x-3\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>=\dfrac{3}{5}\\\left(2x-6\right)\left(12x-12\right)=0\end{matrix}\right.\Leftrightarrow x\in\left\{1;3\right\}\)
b: \(\Leftrightarrow\left|4x+1\right|=8x-x-2=7x-2\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>=\dfrac{2}{7}\\\left(7x-2-4x-1\right)\left(7x-2+4x+1\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>=\dfrac{2}{7}\\\left(3x-3\right)\left(11x-1\right)=0\end{matrix}\right.\Leftrightarrow x=1\)
c: |17x-5|=|17x+5|
=>17x-5=17x+5 hoặc 17x+5=5-17x
=>x=0
37+(13-/2x+7/)=6^30 :(9^14.4^15)
Tìm x
BÀi 1. Tìm x biết
a. | x - 1 | = 2x - 5
8x - | 4x - 1 | = x + 2
b.||x + 5 | - 4| = 3
|17x - 5 | - | 17x + 5 | = 0
c. | 9 - 7x | = 5x-3
|3x4 + 4| = 2 /2x-9/
d. | 10x + 7 | <37
|3 - 8x| lớn hơn hoặc bằng 19
|x+3| -2x=|x-4|