5x-36÷3=28
Hoàn thành phép tính sau:
7/9 + 5/12 - 3/4
=7x4/36 + 5x .../36 - 3x .../36
=28 + ... - .../36
=16/36 = .../...
\(\frac{7}{9}+\frac{5}{12}-\frac{3}{4}\)
\(=\frac{7x4}{36}+\frac{5x3}{36}-\frac{3x9}{36}\)
\(=\frac{28+15-27}{36}\)
\(=\frac{16}{36}=\frac{4}{9}\)
Tìm x biết:
a) 58 + 7x = 100 b) 5x – 7 = 28 c) x – 56 : 4 = 16 d) 101 + (36 – 4x) =105 e) ( x – 12) : 12 = 12 f) (3.x – 24) . 73 = 2.74 g) 71 – (33 + x) = 26 h) 45 – (x + 9):2 = 6 i) 2. (x + 7) – 25 = 13 | k) 2 (x – 51) = 2.23 + 20 l) 450 : (x – 19) = 50 m) 100 – (x – 3) : 2 = 72 – 110 n) 140 : (x – 8) = 7 o) 4 (x + 41) = 400 p) 5 (x – 9) = 350 q) 2x – 49 = 5 . 32 r) 200 – (2x + 6) = 43 s) 135 – 5.(x + 4) = 35 |
a: =>7x=42
hay x=6
b: =>5x=35
hay x=7
c: =>x-14=16
hay x=30
d: =>36-4x=4
=>4x=32
hay x=8
e: =>x-12=144
hay x=156
f: =>3x-16=14
hay x=10
g: =>x+33=45
hay x=12
h: =>(x+9):2=39
=>x+9=78
hay x=69
a: =>7x=42
hay x=6
b: =>5x=35
hay x=7
c: =>x-14=16
hay x=30
d: =>36-4x=4
=>4x=32
Giải phương trình:
a) \(\dfrac{3x-2}{x^2-12x+20}-\dfrac{4x+3}{x^2+6x-16}=\dfrac{7x+11}{x^2-2x-80}\)
b) \(\dfrac{2x-5}{x^2+5x-36}-\dfrac{x-6}{x^2+3x-28}=\dfrac{x+8}{x^2+16x+63}\)
a: \(\Leftrightarrow\dfrac{3x-2}{\left(x-2\right)\left(x-10\right)}-\dfrac{4x+3}{\left(x+8\right)\left(x-2\right)}=\dfrac{8x+11}{\left(x-10\right)\left(x+8\right)}\)
=>(3x-2)(x+8)-(4x+3)(x-10)=(8x+11)(x-2)
=>3x^2+24x-2x-16-4x^2+40x-3x+30=8x^2-16x+11x-22
=>-x^2+59x+14-8x^2+5x+22=0
=>-9x^2+54x+36=0
=>x^2-6x-4=0
=>\(x=3\pm\sqrt{13}\)
b: \(\Leftrightarrow\dfrac{2x-5}{\left(x+9\right)\left(x-4\right)}-\dfrac{x-6}{\left(x+7\right)\left(x-4\right)}=\dfrac{x+8}{\left(x+9\right)\left(x+7\right)}\)
=>(2x-5)(x+7)-(x-6)(x+9)=(x+8)(x-4)
=>2x^2+14x-5x-35-x^2-9x+6x+54=x^2+4x-32
=>x^2+6x+19=x^2+4x-32
=>2x=-51
=>x=-51/2
tìm x
a,x2+5x=0
b,1/21+1/28+1/36+...+2/x(x+1)=2/9
(giúp mk nha mk cần gấp)
a) x2 + 5x = 0
=> x.(x + 5) = 0
=> x = 0 hoặc x + 5 = 0
=> x = 0 hoặc x = -5
b) 1/21 + 1/28 + 1/36 + ... + 2/x(x + 1) = 2/9
=> 2/42 + 2/56 + 2/72 + ... + 2/x(x + 1) = 2/9
=> 2 × [1/6×7 + 1/7×8 + 1/8×9 + ... + 1/x(x + 1)] = 2/9
=> 1/6 - 1/7 + 1/7 - 1/8 + 1/8 - 1/9 + ... + 1/x - 1/x + 1 = 2/9 : 2
=> 1/6 - 1/x + 1 = 2/9 × 1/2 = 1/9
=> 1/x + 1 = 1/6 - 1/9
=> 1/x + 1 = 3/18 - 2/18
=> 1/x + 1 = 1/18
=> x + 1 = 18
=> x = 17
Cách hiểu 1:[TEX]\frac{44-x}{3}[/TEX]=[TEX]\frac{x-12}{5}[/TEX]
[TEX]\frac{220-5x}{15}[/TEX]=[TEX]\frac{3x-36}{15}[/TEX]
hay 220-5x=3x-36
=220-5x-3x+36=0
=220+36-5x-3x=0
=256-(5x+3x)=0
=256-8x=0
=8x=256
=x=32
root(5x + 2, 3) = 3 5sqrt(4x - 16) - 7/3 * sqrt(9x - 36) = 36 - 3sqrt(x - 4)
b:
ĐKXĐ: x>=4
\(5\sqrt{4x-16}-\dfrac{7}{3}\cdot\sqrt{9x-36}=36-3\sqrt{x-4}\)
=>\(5\cdot2\cdot\sqrt{x-4}-\dfrac{7}{3}\cdot3\cdot\sqrt{x-4}+3\sqrt{x-4}=36\)
=>\(6\sqrt{x-4}=36\)
=>\(\sqrt{x-4}=6\)
=>x-4=36
=>x=40
Hoàn thành các phép tính sau :
7/9+5/12-3/4=7×4/36+5×.../36-3×.../36
=28+..._.../36
=16/36=.../...
THUC HIEN PHEP TINH ( TINH NHANH NEU CO THE ) :
1) ( 56 x 46 - 25 x 23 ) : 23
2) ( 28 x 54 + 56 x 36 ) : 21 : 2
3) ( 76 x 34 - 19 x 64 ) : ( 38 x 9 )
4) ( 2 + 4 + 6 + .... + 100 ) x ( 36 x 333 - 108 x 111 )
5) ( 5x 411 - 3 x 165 ) : 410
6) 7256 x 4375 - 725
3650 + 4375 x 7255
3 . ( 5x - 8) = 36
5x-8= 36:3
5x-8= 12
5x=12 +8
5x=20
x=20:5
x=4