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a)
\( 49.(51 - 4) - 51.(49 + 4)\)
\(=49.51-49.4-51.49-51.4\)
\(=49.(51-4-51)-51.4\)
\(=49.(-4)-51.4\)
\(=4.(-49-51)\)
\(=4.(-100)\)
\(=-400\)
b)
\( 71.64 + 32.(-7) - 13.32\)
\(=71.32.2+32.(-7)-13.32\)
\(=142.32+32.(-7)-13.32\)
\(=32.(142-7-13)\)
\(=32.122\)
\(=3904\)
c)
\( 11 + (-13) + 15 + (-17) + ... + 59 + (-61)\)
\(=(-2)+(-2)+...+(-2)\)
\(=(-2).13\)
\(=-26\)
f: =49*51-49*4-51*49-51*4
=-49*5-51*4
=-4*100=-400
h: =41(-328+128)
=-41*200
=-8200
B = 1/4 x( 4/ 1x3x5 +4 /3x5x7 +...+ 4/47x49x51)
= 1/4 x( 1/ 1x3 - 1/3x5 +1/3x5 -1/5x7 +...+ 1/47x49 -1/49x51)
= 1/4 x( 1/1x3 -1/49x51)
= 1/4 x( 1/3 - 1/2499)
= 1/4 x 832/2499
= 208 /2499
Vậy B= 208 /2499
C= 1/ 9x11 -1/ 11x13 +1/ 11x13 -1/ 13x15 +... + 1/ 59x61 -1/61x63
= 1/ 9x11 -1/ 61x63
= 1/99 -1/3843
= 416 /42273
Vậy C= 416 /42273
a, (-17) + 21 + 79 + 17
= (-17 + 17) + (21 + 79)
= 0 + 100
= 100
b, 40 + 22 + (-16) + (-44)
= 40 + {(-16) + (-44} + 22
= 40 - 60 + 22
= - 20 + 22
= 2
c, (-12) + (-47) + (-28) + 47
= - (12 + 28) + (-47 + 47)
= - 40 + 0
= - 40
d, (- 5) + (-3) + 35 + (-17)
= (-5 + 35) - (3 + 17)
= 30 - 20
= 10
a, 3.7.23 - 21.(-17)
= 21.23 + 21.17
= 21.(23 + 17)
= 21.40
= 840
b, 7.6.3 - 7.[(-34) + 18)]
= 7.18 - 7.18 + 34.7
= 34.7
= 238
c, 71.64 + 32.(-7) - 13.32
= 71. 32 . 2 - 7.32 - 32. 13
= 32.(71.2 - 7 - 13)
= 32. (142 - 20)
= 32.122
= 3904
d, 13.(23 - 17) - 13.(23 + 17)
= 13.23 - 13.17 - 13.23 - 13.17
= (13.23 - 13.23) - (13.17 + 13.17)
= - 2.13.17
= - 26.17
= -442
a) \(=\left(\left(-\frac{1}{4}-\frac{5}{3}\right)+\frac{7}{33}\right)-\left(-\frac{15}{12}+\frac{6}{11}-\frac{48}{49}\right)\)
\(=\left(-\frac{23}{12}+\frac{7}{33}\right)+\frac{15}{12}-\frac{6}{11}+\frac{48}{49}\)
\(=\left(-\frac{23}{12}+\frac{15}{12}\right)+\left(\frac{9}{33}-\frac{6}{11}\right)+\frac{48}{49}\)
\(=-\frac{2}{3}-\frac{3}{11}+\frac{48}{49}\)
\(=\frac{65}{1617}\)
b) \(=\frac{11}{125}+\left(-\frac{17}{18}+\frac{4}{9}\right)+\left(-\frac{5}{7}+\frac{17}{14}\right)\)
\(=\frac{11}{125}-\frac{1}{2}+\frac{1}{2}\)
\(=\frac{11}{125}\)
a) 128 + 43 + 72 + 57
= ( 128 + 72 ) + ( 43 + 57 )
= 200 + 100
= 300
b) 41 . 51 + 49 . 51
= 51 . ( 41 + 49 )
= 51 . 90
= 4590
=
\(a,\) \(128+43+72+57\)
\(=\left(128+72\right)+\left(43+57\right)\)
\(=200+100\)
\(=300\)
\(b,\) \(41.51+49.51=51.\left(41+49\right)=51.90=4590\)
\(c,\) \(4^7:4^5=4^{7-5}=4^2=16\)
\(d,\) \(2.\left(5.4^2-18\right)\)
\(=2.\left(5.2^4-2.3^2\right)\)
\(=2.2.\left(5.2^3-3^2\right)\)
\(=4.\left(40-9\right)\)
\(=4.31=123\)
a. 49.51- 49.4 -51.49 -51.4
= -49.4 - 51.4
=4.(-49-51)
=4.-100
=-400
b.71.64 + 32.(-7) -13.32
= 71.64 + 32.(-7-13)
=71.64 + 32.-20
=71.32.2 +32.-20
=32.(71x2-20)
=32. 122
= 3904
c. (11-13)+(15-17)+..+(59-61)
=-2 x 13
=-26