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5,7 * 6,2 + 1,9 * 4,5 + 5,7 *13,3
= 5,7 *( 6,2 + 13,3) +1,9 * 4,5
= 5,7 * 19,5 + 1,9 *4,5
= 111,15 + 8,55
= 120,05
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =-9/11+2/3=-27/33+22/33=-5/33
b: =(16/29-13/29)+12/39-16/39
=3/29-4/39=1/1131
d: =(-111,82-8,18)+(13,3+16,7)=-120+30=-90
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a)\(\left( { - 35,1} \right).\left( { - 64} \right):13 \approx \left( { - 35} \right).\left( { - 64} \right):13 \approx 172\)
b)\(\left( { - 8,8} \right).\left( { - 4,1} \right):{\rm{ }}2,6 \approx ( - 9).( - 4):3 = 12\)
c) \(7,9.\left( { - 73} \right):\left( { - 23} \right) \approx 8.( - 73):( - 23) \approx 25\).
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a) (−4,5) + 3,6 + 4,5 + (−3,6)
= [4,5 + (-4,5)] + [3,6 + (-3,6)]
= 0 + 0 = 0
b) 2,1 + 4,2 + (−7,9) + (−2,1) + 7,9
= [2,1 + (-2,1)] + [(-7,9) + 7,9] + 4,2
= 0 + 0 + 4,2 = 4,2
c) (−3,6) . 5,4 + 5,4 . (−6,4).
= 5,4 . [(−3,6) + (−6,4)]
= 5,4 . (-10)
= -54
a) (−4,5) + 3,6 + 4,5 + (−3,6)
= [4,5 + (-4,5)] + [3,6 + (-3,6)]
= 0 + 0 = 0
b) 2,1 + 4,2 + (−7,9) + (−2,1) + 7,9
= [2,1 + (-2,1)] + [(-7,9) + 7,9] + 4,2
= 0 + 0 + 4,2 = 4,2
c) (−3,6) . 5,4 + 5,4 . (−6,4).
= 5,4 . [(−3,6) + (−6,4)]
= 5,4 . (-10)
= -54
![](https://rs.olm.vn/images/avt/0.png?1311)
a) (-4,5) + 3,6 + 4,5 + (-3,6)
= [(-4,5) + 4,5] + [3,6 + (-3,6)]
= 0 + 0 = 0
b) 2,1 + 4,2 + (-7,9) + (-2,1) + 7,9
= [2,1 + (-2,1)] + [(-7,9) + 7,9] + 4,2
= 0 + 0 + 4,2 = 4,2
c) (-3,6).5,4 + 5,4.(-6,4)
= 5,4. [(-3,6) + (-6,4)]
= 5,4. (-10) = - 54.
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1. A = (-2)(-3) - 5.|-5| + 125.\(\left(-\dfrac{1}{5}\right)^2\)
= 6 - 25 + 125.\(\dfrac{1}{25}\)
= -19 + 5
= -14
@Shine Anna
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a. VT:(x-y)-(x-z)
= x-y-x+z
= z-y
VP:(z+x)-(y+x)
=z+x-y-x
=z-y
=> VT=VP => đpcm.
b. VT:(x-y+z)-(y+z-x)-(x-y)
= x-y+z-y-z+x-x+y
= x-y
VP:(z-y)-(z-x)
= z-y-z+x
= x-y
=> VT=VP => đpcm.
c. VT: a(b+c)-b(a-c)
=ab+ac-ab+bc
= ac+bc
VP: (a+b)c
= ac+bc
=> VT=VP => đpcm.
d. VT: a(b-c)-a(b+d)
= ab-ac-ab-ad
= -ac-ad
VP: -a(c+d)
= -ac-ad
=> VT=VP => đpcm
tương tự...
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a) Vế trái = a.(c + d) + b.( c+ d) - a.(b + c) - d.(b + c)
= a.[(c+ d) - (b + c)] + [b(c+d) - d.(b + c)]
= a.(d - b) + (bc + bd - db - dc) = a.(d - b) + c.(b - d) = a.(d - b) - c.(d - b) = (a - c).(d - b) = Vế phải
Vậy....
b) làm tương tự:
a) (a+b) (c+d) - (a+d) (b+c) = (ac + ad + bc + bd) - (ab + ac +bd + cd) = ac + ad + bc + bd - ab -ac - bd - cd
và bằng ad + bc - ab - cd = a( d-b ) + c( b-d ) = a (d-b) - c (d-b) = (a-c)(d-b) (dpcm)
p/s: ý B chứng minh tương tự.
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a,a-b+c-d=a+c-b-d=(a+c)-(b+d)(đpcm)
b,(a-b)-(c-d)=a-b-c+d=(a+d)-(b+c)(đpcm)
a, Ta có (a-b) +(c-d) = a-b+c-d = (a+c)-(b+d) ( ĐPCM)
b, Ta có (a-b)-(c-d) = a-b-c+d = ( a+d) - ( b+c) ( ĐPCM )
Tk mk nhé
\(B=13,3+\left(-13,3\right)+7,9\\ =\left[13,3+\left(-13,3\right)\right]+7,9\\ =0+7,9\\ =7,9\)
7,9