Bài 2: Tính hợp lý :
a) 32 . 1/243 . 812 . 1/32
b) 46 .2562 . 24
c) A = 46 . 95 + 69 .120 / 84 . 312 - 611
d) B = 42 . 252 + 32 . 125 / 23 . 52
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b:\(1+2+3+...+n=\dfrac{n\left(n+1\right)}{2}\)
c: \(1+3+5+...+37\)
Số số hạng là:
(37-1):2+1=19(số)
Tổng là: \(\dfrac{38\cdot19}{2}=19\cdot19=361\)
4 6 . 9 5 + 6 9 . 120 8 4 . 3 12 − 6 11 = 2 2 6 . 3 2 5 + 2 9 .3 9 .2 3 .3.5 2 3 4 .3 12 − 2 11 .3 11 = 2 12 .3 10 + 2 12 .3 10 .5 2 12 .3 12 − 2 11 .3 11 = 2 12 .3 10 1 + 5 2 11 .3 11 2.3 − 1 = 2.6 3.5 = 4 5
a) -48 + (-35 + 19) - (32 + 45 + 21)
= -48 - 35 + 19 - 32 - 45 - 21
= (-48 - 32) - (35 + 45) + (19 - 21)
= -80 - 80 - 2
= -162
b) -47 + (38 - 13) - (-52 + 31 - 91)
= -47 + 38 - 13 + 52 - 31 + 91
= (-47 - 13) + (38 + 52) - 31
= -60 + 90 - 31
= 30 - 31 = -1
c) 54 + (-37) - (+70) + (-163) - (-246) + (-230
= 54 - 37 - 70 - 163 + 246 - 230
= (54 + 246) - (37 + 163) - (70 + 230)
= 300 - 200 - 300
= -200
còn lại tự lm
1. Q=165+247+528+125+315
= 100+60+5+200+40+7+500+20+8+100+20+5+300+10+5
= ( 100+200+500+100+300) + ( 60+40+20+20+10 ) +( 5+7+8+5+5 )
= 1200+150+30
=1280
R=1234+5678+8+80
=1000+200+30+4+5000+600+70+8+8+80
= ( 1000+5000) + ( 200+600 ) + (30+70+80) + ( 4+8+8)
=6000+800+180+20
=7000
Bài 1
Tính : Q=165+247+528+125+315
=(165+125)+(247+315+528)
=290+1090
= 1380
R=1234+5678+8+80
=(1234+6)+(5678+2)+80
= 1240+5680+80
= (1240+60)+(5680+20)
=1300+5700=7000
Bài 2:
A= 243-97=(243+7)-(97-7)=250-90=160
B= 400-42-58=400-(42+58)=400-100=300
C=600-67-33=600-(67+33)=600-100=500
D=200-24-46=200-(24+46)=200-70=130
E=400-5-6-7-8=400-(5+6+7+8)=400-26=374
F= 764-115-268-43-32-20-85-37
=764-(115+85)-(268+32)-(43+37)-20
=764-200-300-80-20
=164
G=350-7-18-52-48-72
=350-(18+72)-(52+48)-7
=350-90-100-7
=160-7
=153
4 2 . 25 2 + 32. 125 2 3 . 5 2 = 2 4 .5 4 + 2 5 .5 3 2 3 .5 2 = 2 4 .5 3 5 + 2 2 3 .5 2 = 2.5.7 = 70
a)(15 + 37) + (52 -37 -17)
=52+ -2
=50
b) (38- 42 +14) - (23 -21 +10)
=10- 12
=-2
c)- (21 -32) - ( -12 +32)
=10 - 20
=-9
\(Q=165+247+528+125+315\)
\(=\left(247+528+125\right)+\left(165+315\right)\)
\(=900+480\)
\(=1280\)
\(R=1000+200+30+4+5000+600+70+8+80\)
\(=\left(1000+5000\right)+\left(200+600\right)+\left(30+70+80\right)+\left(4+8+8\right)\)
\(=6000+800+180+20\)
\(=6000+\left(800+100\right)+\left(80+20\right)\)
\(=6000+900+100\)
\(=7000\)
a)
(-4) . 32 . (-25) . 11
= (-4).(-25) . (32.11)
= 100 . 352
= 35200
b)
-86 . 46 - 46 . 27 + 46 . 23
= 46. ( -86 - 27 + 23)
= 46. (-90) = -4140
Chúc em học tốt!!!
a)
(-4) . 32 . (-25) . 11
= (-4).(-25) . (32.11)
= 100 . 352
= 35200
P/s tham khảo nha