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a: =-231-16+75+25-9
=-240+100-16
=-140-16=-156
b: =231-17-77=231-94=137
d: =a+b+c-c-b+a=2a
a) - ( 231 + 16 - 75 ) + ( 25 - 9 )
= - 231 - 16 + 75 + 25 - 9
= - 247 + 100 - 9
= -147 - 9
= -156
b) - ( - 231 + 17 ) - ( 54 + 23 )
= 231 + 17 - 54 - 23
= 248 - 31
= 217
c) - [ ( - 25 ) - 7 + ( 8 - 16 ) ] - [ ( - 21 + 3 ) - 7 ]
= - [-32 + (-8) ] - [ -18 - 7]
= - (-40) - (-25)
= 40 + 25
= 65
d) - ( - a - b - c ) + ( - c - b + a )
= a + b + c - c - b + a
= a+ b + 0 - b + a
= a + a + b - b
= a + a + 0
= 2a
e) ( - 26 ) - [ - ( 18 - 6 + 7 ) + ( 8 - 9 ) ]
= -26 - [ -18 + 6 - 7 + 8 - 9]
= -26 - (-20)
= -26 + 20
= -6
1+2+3+4+5+6+7+8+9+10=55
11+12+13+14+15+16+17+18+19+20=155
1+2+3+4+5+6+7+8+9+10+11+12+13+14 +15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30-50-53=362
\(1+2+3+4+5+6+7+8+9+10=55\)
\(11+12+13+14+15+16+17+18+19+20=155\)
a: \(=3\cdot\left(\dfrac{1}{4}-\dfrac{6}{7}+\dfrac{8}{21}\right)\)
\(=3\cdot\left(\dfrac{21}{84}-\dfrac{72}{84}+\dfrac{32}{84}\right)\)
\(=\dfrac{-19}{28}\)
b: \(=\dfrac{-2}{3}\left(\dfrac{1}{9}-\dfrac{1}{6}-\dfrac{1}{11}\right)\)
\(=\dfrac{-2}{3}\cdot\dfrac{-29}{198}=\dfrac{29}{99\cdot3}=\dfrac{29}{297}\)
c: \(=\dfrac{-3}{7}+\dfrac{4}{25}+\dfrac{5}{16}+\dfrac{3}{16}\)
\(=\dfrac{-75+28}{175}+\dfrac{1}{2}\)
\(=\dfrac{-47}{175}+\dfrac{1}{2}=\dfrac{-94+175}{350}=\dfrac{81}{350}\)
d: \(=\dfrac{-4}{9}\cdot\left(\dfrac{1}{26}-\dfrac{1}{2}-\dfrac{1}{8}\right)\)
\(=\dfrac{-4}{9}\cdot\dfrac{-61}{104}=\dfrac{61}{26\cdot9}=\dfrac{61}{234}\)
18 . 26 . 25 . 9
= ( 18 . 25 ) . ( 26 . 9 )
= 450 . 234
= 105 300
2 . 450 . 25 . 8
= ( 2 . 450 ) . ( 25 . 8 )
= 900 . 200
= 180 000
55 . 17 .16 . 15
( 15 . 16 ) . ( 55 . 17 )
= 240 . 935
= 224 400
125 . 98 . 2 . 8 . 25
( 25 .8 ) . ( 125 . 2 ) . 98
= 200 . 250 . 98
= 50 000 . 98
= 4 900 000
15 . 6 . 4 . 125 . 8
= ( 125 . 4 ) . ( 15 . 8 ) . 6
= 500 . 120 . 6
= 60 000 . 6
= 36 000
chúc bạn may mắn . tick cho mình nhé !
a: \(=\left(18\cdot25\right)\cdot9\cdot26=234\cdot450=105300\)
b: \(=\left(25\cdot8\cdot2\right)\cdot450=400\cdot450=180000\)
c: \(=\left(55\cdot17\right)\cdot16\cdot15=240\cdot935=224400\)
d: \(=125\cdot8\cdot2\cdot25\cdot98=98\cdot50\cdot1000=4900000\)
e: \(=125\cdot8\cdot15\cdot4\cdot6=1000\cdot360=360000\)
18 . 26 . 25 . 9
= ( 18 . 25 ) . ( 26 . 9 )
= 450 . 234
= 105 300
2 . 450 . 25 . 8
= ( 2 . 450 ) . ( 25 . 8 )
= 900 . 200
= 180 000
55 . 17 .16 . 15
( 15 . 16 ) . ( 55 . 17 )
= 240 . 935
= 224 400
125 . 98 . 2 . 8 . 25
( 25 .8 ) . ( 125 . 2 ) . 98
= 200 . 250 . 98
= 50 000 . 98
= 4 900 000
15 . 6 . 4 . 125 . 8
= ( 125 . 4 ) . ( 15 . 8 ) . 6
= 500 . 120 . 6
= 60 000 . 6
= 36 000
chúc bạn may mắn . tick cho mình nhé !
S=\(\frac{\left(16+26\right).11}{2}=\frac{42.11}{2}=21.11=231\)
\(P=\frac{\left(1+206\right)206}{2}=\frac{207.206}{2}=103.207=21321\)
a) Số số hạng của S là : ( 26 - 16 ) : 1 + 1 = 11 (số)
S là : ( 26 + 16 ) x 11 : 2 = 231
b) Số số hạng của P là : ( 206 - 1 ) : 1 +1 = 206 (số)
P là : ( 206 + 1 ) x 206 : 2 = 21321