Bài 1: Rút gọn các phân số sau: a/ \(\dfrac{-63}{81}\), b/ \(\dfrac{5.6}{9.35}\), c/ \(\dfrac{7.2+8}{2.14.5}\)
Bài 2: Tìm X: a/ \(\dfrac{4}{7}\)-X = \(\dfrac{1}{2}\). X + \(\dfrac{2}{7}\); b/ X : \(3\dfrac{1}{5}\)= \(1\dfrac{1}{2}\); c/ X . \(\dfrac{3}{4}\)= \(-1\dfrac{5}{8}\)
Bài 3: Tính giá trị biểu thức: A= \(\dfrac{-3}{5}\)+ ( \(\dfrac{-2}{5}\)+ 2 ); B= \(\dfrac{3}{7}\)+ ( -\(\dfrac{1}{5}\) + \(\dfrac{-3}{7}\) ); C= ( -\(\dfrac{5}{24}\) + 0,75 + \(\dfrac{7}{12}\) ) : (-2. \(\dfrac{1}{8}\))
Bài 4: Tìm X: a/ ( \(2\dfrac{1}{3}\) + \(3\dfrac{1}{2}\) ) . X = \(-4\dfrac{1}{6}\) + \(3\dfrac{1}{7}\); b/ X : ( \(3\dfrac{1}{2}\) - \(5\dfrac{1}{6}\) ) = \(4\dfrac{1}{5}\) - \(6\dfrac{2}{3}\)
Các bạn giúp mình nha!
Bài 2.
A = -3/5 + ( -2/5 + 2 )
A = -3/5 + ( -2/5 + 10/5 )
A = -3/5 + 8/5
A = 5/5
A = 1
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B = 3/7 + ( -1/5 + -3/7 )
B = 3/7 + ( -7/35 + -15/35 )
B = 3/7 + ( -22/35 )
B = 15/35 + ( -22/35 )
B = -1/5
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C = ( -5/24 + 0,75 + 7/12 ) : ( -2 . 1/8 )
C = ( -5/24 + 3/4 + 7/12 ) : ( -1/4 )
C = 9/8 : ( -1/4 )
C = 9/8 . ( -4 )
C = -9/2
Bài 3 .
a) 4/7 - x = 1/2 . x + 2/7
<=> -x - x = 1/2 - 4/7 + 2/7
<=> -2x = 3/14
<=> x = 3/14 . ( -1/2 )
<=> x = -3/28
Vậy x = -3/28
b) x : 3 1/5 = 1 1/2
<=> x : 16/5 = 3/2
<=> x = 3/2 . 16/5
<=> x = 24/5
Vậy x = 24/5
c) x . 3/4 = -1 5/8
<=> x . 3/4 = -13/8
<=> x = -13/8 . 4/3
<=> x = -13/6
Vậy x = -13/6
Bài 4.
a) ( 2 1/3 + 3 1/2 ) . x = -4 1/6 + 3 1/7
<=> ( 7/3 + 7/2 ) . x = -25/6 + 22/7
<=> 35/6 . x = -43/42
<=> x = -43/42 . 6/35
<=> x = -43/245
Vậy x = -43/245
b) x : ( 3 1/2 - 5 1/6 ) = 4 1/5 - 6 2/3
<=> x : ( 7/2 - 31/6 ) = 21/5 - 20/3
<=> x : ( 21/6 - 31/6 ) = -37/15
<=> x : ( -5/3 ) = -37/15
<=> x = -37/15 . ( -5/3 )
<=> x = 37/9
Vậy x = 37/9
Bài 1.
a) -63/81 = -63 : 9 / 81 : 9 = -7/9
b) 5 . 6 / 9 . 35 = 5 . 3 . 2 / 3 . 3 . 5 . 7 = 2 / 3 . 7 = 2/21
c) 7 . 2 + 8 / 2 . 14 . 15 = 7 . 2 + 2 . 2 . 2 / 2 . 7 . 2 . 15 = 7 . ( 2 + 2 ) . 2 / 2 . 7 . 2 . 15 = 7 . 2 . 2 . 2 / 2 . 7 . 2 . 15 = 2/15
Cho A = 1/2 .3/4.5/6.....199/200.Chứng tỏ rằng B mũ 2 <1/201.Bạn có làm dược ko ?
Cho A = 1/2 .3/4.5/6.....199/200.Chứng tỏ rằng B mũ 2 <1/201.Bạn có làm dược ko ?