Tính ( -3/4)2
(-2/5)3
(-0,5)2
(- 0,5)3
(9,7)0
Các bn giúp mk nha thank you
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( -3/4 )² ; ( -0,5 )² ; (9,7 )^0
= 9/16 ; = 1/4 ; = 1
( -2/5 )³ ; ( -0,5 )³
= -8/125 ; = -1/8
a: \(x\cdot\dfrac{3}{4}+x=\dfrac{7}{8}\)
\(\Leftrightarrow x\cdot\dfrac{7}{4}=\dfrac{7}{8}\)
\(\Leftrightarrow x=\dfrac{1}{2}\)
\(S=3+\frac{3}{2}+...+\frac{3}{2^9}\)
\(\Rightarrow S=3.\left(1+\frac{1}{2}+...+\frac{1}{2^9}\right)\)
Đặt \(A=1+\frac{1}{2}+...+\frac{1}{2^9}\)
\(\Rightarrow2A=2+1+...+\frac{1}{2^8}\)
\(\Rightarrow2A-A=\left(2+1+...+\frac{1}{2^8}\right)-\left(1+\frac{1}{2}+...+\frac{1}{2^9}\right)\)
\(\Rightarrow A=2-\frac{1}{2^9}\)
Lại có :
\(S=3.A\)
\(\Rightarrow S=3.\left(2-\frac{1}{2^9}\right)\)
\(\Rightarrow S=6-\frac{3}{2^9}\)
Vậy \(S=6-\frac{3}{2^9}\)
Chúc bạn học tốt !!!
a) \(\dfrac{5}{9}:\left(\dfrac{13}{7}+\dfrac{13}{9}\right)-\dfrac{5}{3}\)(chỗ này mk lười chép lại đề)
=\(\dfrac{5}{9}:\dfrac{208}{63}-\dfrac{5}{3}\)
=\(\dfrac{5}{9}.\dfrac{63}{208}-\dfrac{5}{3}\)
=\(\dfrac{5.63}{9.208}-\dfrac{5}{3}\)
=\(\dfrac{5.7}{1.208}-\dfrac{5}{3}\)
=\(\dfrac{36}{208}-\dfrac{5}{3}\)
=\(\dfrac{108}{624}-\dfrac{1040}{624}\)
=\(\dfrac{-932}{624}\)
=\(\dfrac{233}{156}\)
còn câu b mk chưa học nên mk chịu
Giải:
5/9:13/7+5/9:13/9 -1 2/3
=5/9.7/13+5/9.9/13-5/3
=5/9.(7/13+9/13)-5/3
=5/9.16/13-5/3
=80/117-5/3
=-115/117
4 2/5 : 0,5% -1 3/7 .14% +(-0,5)
=22/5:1/200-10/7.7/50 +(-1/2)
=880-1/5-1/2
=8793/10
a,\(0,5-\frac{5}{41}+\frac{1}{2}-\frac{36}{41}\)
=\(\frac{1}{2}-\frac{5}{41}+\frac{1}{2}-\frac{36}{41}\)
=\(\left(\frac{1}{2}+\frac{1}{2}\right)-\left(\frac{5}{41}+\frac{36}{41}\right)\)
= \(1-1=0\)
b,\(\left(\frac{-1}{3}\right)^2.\frac{4}{11}+\frac{7}{11}.\left(\frac{1}{3}\right)^2\)
=\(\frac{1}{9}.\frac{4}{11}+\frac{7}{11}.\frac{1}{9}\)
=\(\frac{1}{9}\left(\frac{4}{11}+\frac{7}{11}\right)\)
=\(\frac{1}{9}.1=\frac{1}{9}\)
c,\(\left(\frac{-2}{3}+\frac{3}{7}\right):\frac{4}{5}+\left(\frac{-1}{3}+\frac{4}{7}\right):\frac{4}{5}\)
=\(\left(\frac{-2}{3}+\frac{3}{7}-\frac{1}{3}+\frac{4}{7}\right):\frac{4}{5}\)
=\(\left(-1+1\right).\frac{5}{4}=0.\frac{5}{4}\)=0
a) 1,2 - ( x - 0,8 ) = -2( 0,9+ x )
<=> 1,2 - x + 0,8 = -1.8 - 2x
<=> x = -3,8
Vậy x = -3,8
b) 2,3x - 2(0,7 + 2x ) = 3,6 - 1,7x
<=> 2,3x - 1,4 - 4x = 3,6 - 1,7x
<=> -3,4x = 5
<=> x = \(\dfrac{-25}{17}\)
Vậy x = \(\dfrac{-25}{17}\)
c) 3(2,2 - 0,3x ) = 2,6 + (0,1x - 4 )
<=> 6,6 - 0,9x = 2,6 + 0,1x - 4
<=> -x = -8
<=> x = 8
Vậy x = 8
d) 3,6 - 0,5(2x + 1) = x- 0,25(2-4x)
<=> 3,6 - x - 0.5 = x - 0,5 + x
<=> -3x = -3,6
<=> x = 1.2
Vậy x = 1.2
a) 3/4+ 1/4:x = 2/5
1/4:x = 3/4-2/5
1/4:x= 7/20
x= 7/20:1/4
x= 7/5
b) chưa học
c) 15/8-1/8: (x/4 - 0,5) = 5/4
1/8: (x/4 -1/2)= 15/8-5/4
1/8:( x/4 -1/2) = 5/8
x/4 - 1/2 = 1/8:5/8
x/4 -1/2= 1/5
x/4= 1/5+1/2
x/4 = 7/7
x/4= 7/7× 4/4
x/4= 28/28
4/4=28/28
phần c ko chắc chắn
đúng k nhé