Chọn cách tính thuận tiện nhất: 65 + 35 + 88 + 12 = ..........
A. (65 + 12) + (35 + 88) = 77 + 123 = 200
B. (65 + 88) + (35 + 12) = 153 + 47 = 200
C. (65 + 35) + (88 + 12) = 100 + 100 = 200
D. Tất cả đều đúng
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a) (12-46)+(46+88)
= 12-46+46+88
= (12+88)+[(-46)+46]
= 100+0
=100.
b) (14+67)+(33-14+100)
= 14+67+33-14+100
=[ [14+(-14)]+[(67+33)+100]
= 0+200
= 200.
c) (35+12-47)-(12+53+65)
= 35+12-47-12-53-65
=[12+(-12)]+[(-47)+(-53)]+[35+(-65)]
=0+(-100)+(-30)
=(-100)+(-30)
=-130.
Chúc bạn học tốt !!!
a) (12-46)+(46+88)=12-46+46+88
=(12+88)-(46-46)=100
b) (14+67)+(33-14+100)=14+67+33-14+100
=(14-14)+100+(67+33)=100+100=200
c) (35+12-47)-(12+53+65)=35+12-47-12-53-65
=(12-12)-(47+53)-(65-35)= -100-30
=-130
12+99+88+1+35+24+65+76
=(12+88)+(99+1)+(35+65)+(24+76)
=100+100+100+100
=400
=(12+88) +(34+46)*2+(55+65)=100+2*80+120=100+160+120=380
b, 53 + 45 + 135 + 147 + 50
= ( 53 + 147 ) + ( 45 + 135 ) + 50
= 200 + 180 + 50
= 200 + 330
= 530
b, 53 + 45 + 135 + 147 + 50
=(53+147)+(45+135+50)
=200+230
=430
= 35*(20,10-19,45)+65*(20,10-19,45)
=35*0,65+65*0,65
=0,65*(35+65)
=0,65*100
=65
\(12+3\cdot3^5:4-3\)
\(=4\cdot3+3^6\cdot\dfrac{1}{4}-3\)
\(=3\cdot\left(4+3^5\cdot\dfrac{1}{4}-1\right)\)
\(=3\cdot\left(3+3^5\cdot\dfrac{1}{4}\right)\)
\(=3\cdot3\cdot\left(1+3^4\cdot\dfrac{1}{4}\right)\)
\(=9\cdot\dfrac{85}{4}\)
\(=\dfrac{785}{4}\)
_________________
\(90^3-88\cdot3\cdot3^9\cdot3\)
\(=9^3\cdot10^3-88\cdot3^{11}\)
\(=\left(3^2\right)^3\cdot10^3-88\cdot3^{11}\)
\(=3^6\cdot1000-88\cdot3^{11}\)
\(=3^6\cdot\left(1000-88\cdot3^5\right)\)
\(=3^6\cdot-20384\)
\(=-14859936\)
________________
\(10^2+10^3+10^4+10^5+10^6\)
\(=\left(10^2+10^3\right)+\left(10^4+10^5\right)+10^6\)
\(=10^2\cdot\left(1+10\right)+10^4\cdot\left(1+10\right)+10^6\)
\(=11\cdot\left(10^2+10^4\right)+10^6\)
\(=11\cdot\left(100+10000\right)+10^6\)
\(=11\cdot10100+1000000\)
\(=111100+1000000\)
\(=1111100\)
_______________
\(7-3:2\cdot7^{10}\)
\(=7\cdot\left(1-\dfrac{3}{2}\cdot7^9\right)\)
\(=7\cdot-60530409,5\)
\(=-423712866,5\)
C
C