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65 . (- 45 ) – 35. 45 + 24 .( -21 )+ 76.( -21 )
=65.(-1).45-35.45+24.(-21)+76.(-21)
=45.(-65-35)+(-21).(24+76)
=45.(-100)+(-21).100
=-4500-2100
=-6600
65 . (- 45 ) – 35. 45 + 24 .( -21 )+ 76.( -21 )
= ( 65 + 35 ) . ( 76 + 24 ) . ( -21) - (-21) . ( 45 + (-45)
= 100 . 100 . 0 .0
= cuối cùng thì đều bằng 0
\(a,30\cdot6+30\cdot71+20\cdot30\)
=\(30\cdot\left(6+71+20\right)\)
=\(30\cdot97=2910\)
\(b,24\cdot\left(31+119\right)+76\cdot\left(29+121\right)\)
=\(24\cdot150+76\cdot150\)
=\(150\cdot\left(24+76\right)\)
=\(150\cdot100\)
=\(15000\)
\(c,87\cdot23+70\cdot87+43\cdot93\)
=\(87\cdot\left(23+87\right)+43\cdot93\)
=\(87\cdot110+3999\)
=\(9570+3999\)
=13569
a) 15 . 6 . 2 + 3 . 71 . 10 + 20 . 30
= ( 15 . 2 ) . 6 + ( 3 . 10 ) . 71 + 20 . 30
= 30 . 6 + 30 . 71 + 20 . 30
= 30 . ( 6 + 71 + 30 )
= 30 . 107
= 3210
b) 24 . 31 + 24 . 119 + 76 . 29 + 76 . 121
= 24 . ( 31 + 119 ) + 76 . ( 29 + 121 )
= 24 . 150 + 76 . 150
= 150 . ( 24 + 76 )
= 150 . 100
= 15 000
c) 87 . 23 + 43 . 93 + 70 . 87
= 87 . 23 + 70 . 87 + 43 . 93
= 87 . ( 23 + 70 ) + 43 . 93
= 87 . 93 + 43 . 93
= 93 . ( 87 + 43 )
= 93 . 130
= 12 090
\(76.\left(-42\right)+76.\left(-14\right)+24.\left(-56\right)\)
\(=76.\left(-42+-14\right)+24.\left(-56\right)\)
\(=76.\left(-56\right)+24.\left(-56\right)\)
\(=\left(76+24\right).-56\)
\(=100.-56\)
\(=-5600\)
a) 998+ 45= 1043.
b) 57+ 195= 252.
c) 497+ 64= 561.
d) 25. 24= 600.
e) 49. 101= 4949.
g) 19. 64+ 76. 34= 3800.
h) 35. 12+ 65. 13= 1265.
a, 18.(-24) + 35.42 - 18.76 + 35.(-142)
= [ 18.(-24) - 18.76] + (35.42 + 35(-142)]
= -18.[ 24 + 76] - 35.( 142 - 42)
= -18.100 - 35. 100
= - 100.(18 + 35)
= - 100. 53
= - 5300
h, 104 : (-13) - [56 - 220 : (-4)]
= 104 : (-13) - [ 56 + 55]
= -8 - 111
= - 119
Đặt A=\(\dfrac{4^2}{20.24}+\dfrac{4^2}{24.28}+...+\dfrac{4^2}{76.80}\)
A=\(\dfrac{16}{20.24}+\dfrac{16}{24.28}+...+\dfrac{16}{76.80}\)
A=4.[\(\dfrac{4}{20.24}+\dfrac{4}{24.28}+...+\dfrac{4}{76.80}\)]
A=4.\(\left[\dfrac{1}{20}-\dfrac{1}{24}+\dfrac{1}{24}-\dfrac{1}{28}+...+\dfrac{1}{76}-\dfrac{1}{80}\right]\)
A=4.\(\left[\dfrac{1}{20}+\dfrac{1}{24}-\dfrac{1}{24}+\dfrac{1}{28}-\dfrac{1}{28}+...+\dfrac{1}{78}-\dfrac{1}{78}-\dfrac{1}{80}\right]\)
A=4.\(\left[\dfrac{1}{20}-\dfrac{1}{80}\right]\)
A=4.\(\dfrac{3}{80}\)
A=\(\dfrac{3}{20}\)<1
=>A<1
Tick mink nha
giúp mình với
45 . 76 + 24 . 175 – 24 . 130
= 45 . 76 + 24. ( 175 - 130 )
= 45 . 76 + 24 . 45
= 45 . (76 + 24)
= 45 . 100
= 4500
# HOK TỐT #