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A= (3,1 - 2,5) - (-2,5 + 3,1)
=3.1-2.5+2.5-3.1
=0
B= (5,3 - 2,8) - (4 + 5,3)
=5.3 - 2.8-4-5.3
= -6.8
C= -(251.3 + 281) + 3.251 - (1-281)
=-251.3-281+3.251-1+281
=-1
D= -(3/5+3/4)−(−3/4+2/5)
= -3/5-3/4+3/4-2/5
= -5/5
=-1
\(A=\left(3,1-2,5\right)-\left(-2,5+3,1\right)=3,1-2,5+2,5-3,1=0\)
\(B=\left(5,3-2,8\right)-\left(4+5,3\right)=5,3-2,8-4-5,3=-6,8\)
\(C=-\left(215\cdot3+281\right)+3\cdot215-\left(1-281\right)=-215\cdot3-281+3\cdot215-1+281=1\)
\(D=-\left(\frac{3}{5}+\frac{3}{4}\right)-\left(-\frac{3}{4}+\frac{2}{5}\right)=-\frac{3}{5}-\frac{3}{4}+\frac{3}{4}-\frac{2}{5}=-1\)
A = \(\left(3,1-2,5\right)-\left(-2,5+3,1\right)\)
\(=3,1-2,5+2,5-3,1=6,2\)
B = \(\left(5,3-2,8\right)-\left(4+5,3\right)\)
\(=5,3-2,8-4-5,3=-6,8\)
C = \(-\left(251.3+281\right)+3.251-\left(1-281\right)\)
\(=-251.3-281+3.251-1+281=-1\)
D = \(-\left(\frac{3}{5}+\frac{3}{4}\right)-\left(-\frac{3}{4}+\frac{2}{5}\right)\)
\(=-\frac{3}{5}-\frac{3}{4}+\frac{3}{4}-\frac{2}{5}=-1\)
(Nhớ k cho mình với nhá!)
1a, (-3,8) + [ (-5,7)+3,8]
= (-3,8+3,8) -5,7
= -5,7
b, 31,4 +[6,4 +(-18)]
= 31,4 - 11,6
= 19,8
c,[(9,6 )+4,5 ] +[9,6 +(-1,5)]
= 9,6 +9,6 +(4,5-1,5)
= 19,2 +3
=22,2
d, [ (-4,9) + (-7,8)] +[1,9+2,8]
= (-4,9 +1,9)+ (-7,8+2,8)
= -3 -5
=-8
e, (3,1-2,5)-(-2,5+3,1)
= (3,1-3,1)+(2,5-2,5)
=0
f, (5,3 -2,8 )- (4+5,3)
= (5,3-5,3) -2,8-4
= -6,8
g, -(251,3 +281 )+ 3,251 -(1-281)
= -251,3-281+3,251 -1+281
= (-281+281) -251,3 +3,251 -1
= -249,049
h,-(3/54+3/4)-(-3/4 +2/5)
= -3/54-3/4 +3/4 +2/5
=(-3/4+3/4) -3/54 +2/5
=123/270
chúc bạn học tốt
\(a,\left(7+3\dfrac{1}{4}-\dfrac{3}{5}\right)+\left(0,4-5\right)-\left(4\dfrac{1}{4}-1\right)\)
\(=\left(7+\dfrac{13}{4}-\dfrac{3}{5}\right)-\dfrac{23}{5}-\left(\dfrac{17}{4}-1\right)\)
\(=7+\dfrac{13}{4}-\dfrac{3}{5}-\dfrac{23}{5}-\dfrac{17}{4}+1\)
\(=\left(7+1\right)+\left(\dfrac{13}{4}-\dfrac{17}{4}\right)-\left(\dfrac{3}{5}+\dfrac{23}{5}\right)\)
\(=8-\dfrac{4}{4}-\dfrac{26}{5}\)
\(=7-\dfrac{26}{5}\)
\(=\dfrac{9}{5}\)
\(b,\dfrac{2}{3}-\left[\left(-\dfrac{7}{4}\right)-\left(\dfrac{1}{2}+\dfrac{3}{8}\right)\right]\)
\(=\dfrac{2}{3}-\left(-\dfrac{7}{4}-\dfrac{1}{2}-\dfrac{3}{8}\right)\)
\(=\dfrac{2}{3}-\left(-\dfrac{14}{8}-\dfrac{4}{8}-\dfrac{3}{8}\right)\)
\(=\dfrac{2}{3}-\left(-\dfrac{21}{8}\right)\)
\(=\dfrac{2}{3}+\dfrac{21}{8}\)
\(=\dfrac{79}{24}\)
\(c,\left(9-\dfrac{1}{2}-\dfrac{3}{4}\right):\left(7-\dfrac{1}{4}-\dfrac{5}{8}\right)\)
\(=\left(\dfrac{36}{4}-\dfrac{2}{4}-\dfrac{3}{4}\right):\left(\dfrac{56}{8}-\dfrac{2}{8}-\dfrac{5}{8}\right)\)
\(=\dfrac{31}{4}:\dfrac{49}{8}\)
\(=\dfrac{62}{49}\)
\(d,3-\dfrac{1-\dfrac{1}{7}}{1+\dfrac{1}{7}}=3-\dfrac{\dfrac{7}{7}-\dfrac{1}{7}}{\dfrac{7}{7}+\dfrac{1}{7}}=3-\left(\dfrac{6}{7}:\dfrac{8}{7}\right)=3-\dfrac{3}{4}=\dfrac{9}{4}\)
Tính nhanh:
a) (-6,37 × 0,4) × 2,5;
b) (-0,125) × (-5,3) × 8;
c) (-2,5) × (-4) × (-7,9);
d) (-0,375) × 413(−2)3413(−2)3
Hướng dẫn làm bài:
a) (- 6,37 × 0,4) × 2,5
= - 6,37× (0,4 × 2,5)
= - 6,37 × 1 = - 6,37
b) (-0,125) × (-5,3) × 8
= (-0,125 × 8) × (-5,3)
=(-1). (-5,3) = 5,3
c) (-2,5) × (-4) × (-7,9)
= [(-2,5) × (-4)] × (-7,9)
= 10 . (-7,9)
= -79
d) (−0,375).413.(−2)3
=[(−0,375).(−8)].133=[(−0,375).(−8)].133
=3.133=13
a) \(=\dfrac{\left(-1\right)^4}{3^4}=\dfrac{1}{81}\)
b) \(=\dfrac{\left(-9\right)^3}{4^3}=\dfrac{-729}{64}\)
c) \(=\left(-\dfrac{2}{10}\right)^2=\left(-\dfrac{1}{5}\right)^2=\dfrac{1}{25}\)
d) \(=1\)
\(a,=\dfrac{1}{81}\\ b,=\dfrac{729}{64}\\ c,=0,04\\ d,=1\)
a) = (\(-\dfrac{141}{20}\)- \(\dfrac{1}{4}\)) : (-5) + \(\dfrac{1}{15}\) - \(\dfrac{1}{15}\)
= \(-\dfrac{73}{10}\) : - 5
= \(\dfrac{73}{50}\)
b) = \(\left(\dfrac{3}{25}-\dfrac{28}{25}\right)\). \(\dfrac{7}{3}\) : \(\left(\dfrac{7}{2}-\dfrac{11}{3}.14\right)\)
= \(-\dfrac{7}{3}\) . \(-\dfrac{6}{287}\)
= \(\dfrac{2}{41}\)
\(A=\left(3,1-2,5\right)-\left(-2,5+3,1\right)\)
\(A=3,1-2,5+2,5-3,1\)
\(A=\left(3,1-3,1\right)-\left(2,5-2,5\right)\)
\(A=0-0\)
\(A=0\)
\(B=\left(5,3-2,8\right)-\left(4+5,3\right)\)
\(B=5,3-2,8-4-5,3\)
\(B=\left(5,3-5,3\right)-\left(2,8+4\right)\\ B=0-6,8\\ B=-6,8\)