Bài 2
a) 1/2 x - 2/3 = -5/4
1/2 x = -5/4 + 2/3
1/2 x =
1/2 x = -7/12
x = -7/12 : 1/2
x = -7/6
b) 1/2 + 3/2 x = -5/4
3/2 x = -5/4 - 1/2
3/2 x = -7/4
x = -7/4 : 3/2
x = -7/6
c) -1/3 - 3/4 x = -5/6
3/4 x = -1/3 - (-5/6)
3/4 x = 1/2
x = 1/2 : 3/4
x = 2/3
d) 11/12 - (2/5 + x) = 2/3
2/5 + x = 11/12 - 2/3
2/5 + x = 1/4
x = 1/4 + 2/5
x = 13/20
e) 3/7 - (1/2 - x) = 5/14
1/2 - x = 3/7 - 5/14
1/2 - x = 1/14
x = 1/2 - 1/14
x = 3/7
g) 3/5 - x = 7/10 - (-1/2)
3/5 - x = 6/5
x = 3/5 - 6/5
x = -3/5
h) x - (7/5 - 4/3) = -8/15
x - 1/15 = -8/15
x = -8/15 + 1/15
x = -7/15
i) -2/3 + 5x = -8/15 - x
5x + x = -8/15 + 2/3
6x = 2/15
x = 2/15 : 6
x = 1/45
k) 3^x + 3^(x + 2) = 810
3^x . (1 + 3²) = 810
3^x . 10 = 810
3^x = 810 : 10
3^x = 81
3^x = 3⁴
x = 4
n) 5/8 - (1/3 + x)³ = 1/2
(1/3 + x)³ = 5/8 - 1/2
(1/3 + x)³ = 1/8
(1/3 + x)³ = (1/2)³
1/3 + x = 1/2
x = 1/2 - 1/3
x = 1/6
m) 5/9 + (1/2 - x)² = 4/9
(1/2 - x)² = 5/9 - 4/9
(1/2 - x)² = 1/9
(1/2 - x)² = (1/3)² hoặc (1/2 - x)² = (-1/3)²
1/2 - x = 1/3 hoặc 1/2 - x = -1/3
*) 1/2 - x = 1/3
x = 1/2 - 1/3
x = 1/6
*) 1/2 - x = -1/3
x = 1/2 - (-1/3)
x = 5/6
Vậy x = 1/6; x = 5/6
o) 125⁴ : 5^x = 25⁵
(5³)⁴ : 5^x = (5²)⁵
5¹² : 5^x = 5¹⁰
5^x = 5¹² : 5¹⁰
5^x = 5²
x = 2
Bài 1
a) 3 - (-6/7)⁰ + (1/2)² : 2
= 3 - 1 + 1/4 : 2
= 2 + 1/8
= 17/8
b) 2/9 - 11/9 : (-1/2)²
= 2/9 - 11/9 : 1/4
= 2/9 - 44/9
= -14/3
c) 7/38 . 9/11 + 7/38 . 4/11 - 7/38 . 2/11
= 7/38 . (9/11 + 4/11 - 2/11)
= 7/18 . 1
= 7/18
d) -5/17 . 31/33 + (-5/17) : 33/2 + 2 5/17
= -5/17 . 31/33 + (-5/17) . 2/33 + 39/17
= -5/17.(31/33 + 2/33) + 39/17
= -5/17 . 1 + 39/17
= -5/17 + 39/17
= 2
e) (-2 1/5 + 2/7 - 12/13) - (-5/7 + 1/13)
= -11/5 + 2/7 - 12/13 + 5/7 - 1/13
= (2/7 + 5/7) - (12/13 + 1/13) - 11/5
= 1 - 1 - 11/5
= -11/5
f) (-11/14 + 2/11 - 19/13) - (-9/11 + 3/14 - 6/13)
= -11/14 + 2/11 - 19/13 + 9/11 - 3/14 + 6/13
= (-11/14 - 3/14) + (-19/13 + 6/13) + (2/11 + 9/11)
= -1 - 1 + 1
= -1
