Tìm x biết x: 46/15 -3/4 = 9/4
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A) x/13+15/26=46/52
x/13+15/26=23/26
x/13=23/26-15/26
x/13=4/13
x=4
a) \(x+546=46\\ x=46-546\\ x=-500\)
b) \(2x-19\times3=27\\ 2x-57=27\\ 2x=27+57\\ 2x=84\\ x=84:2\\ x=42\)
c) \(x+12=23+3\times3^4\\ x+12=23+3\times81\\ x=23+243-12\\ x=254\)
d) \(x-12=3-3\times2^4\\ x-12=3-3\times16\\ x=3-48+12\\ x=-33\)
e) \(\left(27-x\right)\left(x+9\right)=0\\ \Rightarrow\left[{}\begin{matrix}27-x=0\\x+9=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=27\\x=-9\end{matrix}\right.\)
f) \(\left(-x\right)\left(x-43\right)=0\\ \Rightarrow\left[{}\begin{matrix}-x=0\\x-43=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=0\\x=43\end{matrix}\right.\)
2 x X + 68 = 126
2 x X = 126 - 68
2 x X = 58
x = 58 : 2
x = 29
a: Ta có: \(\left(x+2\right)\left(x^2-2x+4\right)-x\left(x^2+2\right)=15\)
\(\Leftrightarrow x^3+8-x^3-2x=15\)
\(\Leftrightarrow2x=-7\)
hay \(x=-\dfrac{7}{2}\)
b: Ta có: \(\left(x-2\right)^3-\left(x-4\right)\left(x^2+4x+16\right)+6\left(x+1\right)^2=49\)
\(\Leftrightarrow x^3-6x^2+12x-8-x^3+64+6\left(x+1\right)^2=49\)
\(\Leftrightarrow-6x^2+12x+56+6x^2+12x+6=49\)
\(\Leftrightarrow24x=-13\)
hay \(x=-\dfrac{13}{24}\)
Bài 3:
a) 11 - (15 + 11) = x - (25 - 9)
=> 11 - 15 - 11 = x - 25 + 9
=> x = 9 - 25 + 15
=> x = -1
b) 2 - x = 17 - (-5)
=> 2 - x = 17 + 5
=> -x = 17 + 5 - 2
=> -x = 20
=> x = -20
c) x - 12 = (-9) - 15
=> x - 12 = -9 - 15
=> x = -9 - 15 + 12
=> x = -12
d) IxI - 7 = 9
=> IxI = 9 + 7
=> IxI = 16
=> x = 16 hay x = -16
e) 9 - 25 = (7 - x) - (25 + 7)
=> 9 - 25 = 7 - x - 25 - 7
=> x = 7 - 7 - 25 + 25 - 9
=> x = -9
Bài 4:
a) 25 . 46 + 54 . 25
= 25(46 + 54)
= 25.100
= 2500
b) 1200 : 25
= (25.48) : 25
= 25:25 . 48
= 1.48
= 48
c) 1356 - 998
= 1356 + 2 - 998 - 2
= 1358 - 1000
= 358
d) 117 + 57 - 17
= 117 - 17 + 57
= 100 + 57
= 157
Bài 5:
a) 34 . 315
= 34 + 15
= 319
b) 88 : 88
= 88 - 8
= 80
= 1
c) 100 - [120 - (15 - 5)2 ]
= 100 - (120 - 102)
= 100 - (120 - 100)
= 100 - 120 + 100
= 80
Bài 3 :
a, 11 - ( 15 + 11 ) = x - ( 25 - 9 )
11 - 26 = x - 16
- 15 = x - 16
x = - 15 + 16
x = 1
b, 2 - x = 17 - ( - 5 )
2 - x = 22
x = 2 - 22
x = - 20
c, x - 12 = - 9 - 15
x - 12 = - 24
x = - 24 + 12
x = - 12
d, | x | - 7 = 9
| x | = 9 + 7
| x | = 16
x = 16 hoặc - 16
e, 9 - 25 = ( 7 - x ) - ( 25 + 7 )
- 16 = 7 - x - 32
x = 7 - 32 + 16
x = - 9
Bài 4 :
25 x 46 + 54 x 25
= 25 x ( 46 + 54 )
= 25 x 100
= 2500
b, 1200 : 25
= 12 x 100 : 25
= 12 x 4
= 48
c, 1356 - 998
= 358
d, 117 + 57 - 17
= ( 117 - 17 ) + 57
= 100 + 57
= 157
Bài 5 :
a, 3^4 . 3^15
= 3^19
b, 8^8 : 8^8
= 1
c, 100 - [ 120 - ( 15 - 5 )^2 ]
= 100 - ( 120 - 100 )
= 100 - 20 = 80
bai 4 : a) = 2500
b)=48
c)=157
bai 5 : a)= 1162261467
b)=1
c)= 80
x : 46/15 -3/4 = 9/4
x: 46/15 = 9/4 + 3/4
x: 46/15 = 3
x = 3 x 46/15 = 46/5
x : 46/15 -3/4 = 9/4
x: 46/15 = 9/4 + 3/4
x: 46/15 = 3
x = 3 x 46/15 = 46/5