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a,(-67.77) - (-67.44) - 77.44+77.67
= (-67).(77-44)-77.(44+67)
= (-67-77).(77-44+44+67)
=-144.144
=-20736
b,[-36:(-12)]-12.8+63-1
=3-12.8+216-1
=3-96+216-1
=122
![](https://rs.olm.vn/images/avt/0.png?1311)
a, Ta có: 339 < 340 = (32)20 = 920
1121 > 1120
Vì 9 < 11 => 920 < 1120 => 339 < 1121
b, Ta có: 1245 - 1244 = 1244(12 - 1) = 1244.11
1244 - 1243 = 1243(12 - 1) = 1243.11
Vì 1244 > 1243 => 1244.11 > 1243.11 => 1245 - 1244 > 1244 - 1243
c, Đặt A = 1+2+22+....+29
2A = 2+22+23+...+210
2A-A=210-1
A=210-1
Ta có: 5.28 = 28.4 > 28.4 - 1 = 210 - 1
Vậy A < 5.28
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a) 51 × (-15) + (-15) × 49
= -15 × (51 + 49)
= -15 × 100
= -1500
b) 4 × (5 - 8) + 8 × 4
= 4 . 5 - 4 × 8 + 8 × 4
= 20 - 32 + 32
= 20 + 0
= 20
c) 43 + (-7) - 43 + (-93)
= (43 - 43) - (7 + 93)
= 0 - 100
= -100
d) (44 + 8) - (-2 + 44)
= 44 + 8 + 2 - 44
= (44 - 44) + (8 + 2)
= 0 + 10
= 10
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a) Số lượng số hạng:
\(\left(44-4\right):4+1=11\) (số hạng)
Tổng dãy số là:
\(A=\left(44+4\right)\cdot11:2=264\)
b) Số lượng số hạng:
\(\left(135-3\right):3+1=45\) (số hạng)
Tổng dãy số là:
\(B=\left(135+3\right)\cdot45:2=3105\)
c) Số lượng số hạng:
\(\left(250-5\right):5+1=50\) (số hạng)
Tổng dãy số là:
\(C=\left(250+5\right)\cdot50:2=6375\)
`a,` Khoảng cách : `2`
Số số hạng : \(\dfrac{44-4}{2}+1=21\)
Tổng dãy là : \(\dfrac{\left(44+4\right)\cdot21}{2}=504\)
`b,` Khoảng cách : `3`
Số số hạng là : \(\dfrac{135-3}{3}+1=45\)
Tổng dãy là : \(\dfrac{\left(135+3\right)\cdot45}{2}=3105\)
`c,` Khoảng cách là : `5`
Số số hạng là : \(\dfrac{250-5}{5}+1=50\)
Tổng dãy là : \(\dfrac{\left(250+5\right)\cdot50}{2}=6375\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\left(x-2\right)^2-11=25\)
\(\left(x-2\right)^2=25+11\)
\(\left(x-2\right)^2=36\)
\(\left(x-2\right)^2=6^2\)
\(\Rightarrow x-2=6\)
\(\Rightarrow x=8\)
vậy \(x=8\)
những câu khác làm tương tự
học vui truong the dat
a, \(\left(x-2\right)^2-11=25\)
\(\Rightarrow\left(x-2\right)^2=25+11\)
\(\Rightarrow\left(x-2\right)^2=36\)
\(\Rightarrow\left(x-2\right)^2=6^2=\left(-6\right)^2\)
\(\Rightarrow x-2=6\)hoặc \(x-2=-6\)
\(\Rightarrow x\in\left\{8;-4\right\}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a.
$-12-(-46)=-12+46=46-12=34$
b.
$-(-8)-54=8-54=-(54-8)=-46$
c.
$-15-(-72)=-15+72=72-15=57$
Bài 2:
a. $(156-812)-(156-12)=156-812-156+12$
$=(156-156)-(812-12)=0-800=-800$
b.
$-(-72+83)-(72+17)=72-83-72-17=(72-72)-(83+17)$
$=0-100=-100$
c.
$-(-23-78)+(77-178)=23+78+77-178$
$=(23+77)-(178-78)=100-100=0$
d.
$(-213-156)-(-213+44)=-213-156+213-44=(-213+213)-(156+44)$
$=0-200=-200$
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{7}{16}+\dfrac{-1}{8}+\dfrac{9}{32}=\dfrac{14}{32}-\dfrac{4}{32}+\dfrac{9}{32}=\dfrac{19}{32}\)
\(\dfrac{5}{4}-\dfrac{25}{30}\times\dfrac{37}{44}+\dfrac{-25}{30}\times\dfrac{13}{44}+\dfrac{-25}{30}\times\dfrac{-6}{44}\)
\(=-\dfrac{25}{30}\times\left(\dfrac{5}{4}+\dfrac{37}{44}+\dfrac{13}{44}-\dfrac{6}{44}\right)\)
\(=-\dfrac{25}{30}\times\left(\dfrac{55}{44}+\dfrac{37}{44}+\dfrac{13}{44}-\dfrac{6}{44}\right)\)
\(=-\dfrac{25}{30}\times\dfrac{99}{44}\)
\(=-\dfrac{5}{6}\times\dfrac{9}{4}\)
\(=-\dfrac{15}{8}\)
\(\left(\dfrac{7}{16}+\dfrac{-1}{8}+\dfrac{9}{32}\right):\dfrac{5}{4}\)
\(=\left(\dfrac{14}{32}+\dfrac{-4}{32}+\dfrac{9}{32}\right):\dfrac{5}{4}\)
\(=\dfrac{19}{32}:\dfrac{5}{4}\)
\(=\dfrac{19}{32}.\dfrac{4}{5}=\dfrac{19.4}{32.5}=\dfrac{19}{40}\)
\(\dfrac{-25}{30}.\dfrac{37}{44}+\dfrac{-25}{30}.\dfrac{13}{44}+\dfrac{-25}{30}.\dfrac{-6}{44}\)
\(=\dfrac{-25}{30}.\left(\dfrac{37}{44}+\dfrac{13}{44}+\dfrac{-6}{44}\right)\)
\(=\dfrac{-25}{30}.\dfrac{44}{44}=\dfrac{-5}{6}.1=-\dfrac{5}{6}\)
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1: 243^5=(3^5)^5=3^25
3*27^8=3*(3^3)^8=3^25
=>243^5=3*27^8
6: 125^5=(5^3)^5=5^15
25^7=(5^2)^7=5^14
=>125^5>25^7(15>14)
5: 78^12-78^11=78^11(78-1)=78^11*77
78^11-78^10=78^10*77
mà 11>10
nên 78^12-78^11>78^11-78^10
![](https://rs.olm.vn/images/avt/0.png?1311)
a)3.(x-30)+5.(-2-x) = 12-44
\(\Rightarrow3x-90-10-5x=12-44\)
\(\Rightarrow3x-90-10-5x-12+44=0\)
\(\Rightarrow-2x-68=0\)
\(\Rightarrow-2x=68\)
\(\Rightarrow x=-34\)
Vây: \(x=-34\)
b)-2.(x-4) + (-4-4x) = -x + 1
\(\Rightarrow-2x+8-4-4x=-x+1\)
\(\Rightarrow-2x+8-4-4x+x-1=0\)
\(\Rightarrow-5x+3=0\)
\(\Rightarrow-5x=-3\)
\(\Rightarrow x=\frac{3}{5}\)
Vậy: \(x=\frac{3}{5}\)
\(12.x-44=-8\)
\(12.x=-8+44\)
\(12.x=36\)
\(x=36:12\)
\(x=3\)