Tính bằng cách hợp lý nhất:
a) 714 + 382 + 286 + 318
b) 125.98.2.8.25
c) 78.31 + 78.24 + 22.17 + 22.38
d) 53.(51 + 4) + 53.(49 + 95) + 53
e) 5 + 9 + 13 + 17 + … + 201
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a, 16.(27+15)+8.(53+25):2
= 4.[(27+15).4] + 4.(53+25)
= 4.168 + 4.312
= 4.(168+312)
= 4.480=1920.
...
Câu b tình bt thui!
b, 53.(51+4)+53.53.(49+96)+53
=53.55+53.53.145+53
=2915+407305+53
=410220+53=410273
a) \(\text{13 x 58 x 4 + 32 x 26 x 2 + 52 x 10 }\)
\(\text{=(13 x 4 ) x 58 + 32 x 13 x 2 x 2 + 13 x 4 x 10}\)
\(\text{= ( 13 x 4 ) x 58 + 32 x ( 13 x 2 x 2 ) + ( 13 x 4 ) x 10 }\)
\(\text{= 52 x 58 + 32 x 52 + 52 x 10}\)
\(\text{=52 x ( 58 + 32 + 10 )}\)
\(\text{=52 x 100 = 5200}\)
b) \(\text{14 x 35 x 5 + 10 x 25 x 7 + 20 x 70 x 2}\)
\(\text{= ( 14 x 5 ) x 35 + (10 x 7 ) x 25 + 20 x 70 x 2 }\)
\(\text{= 70 x 35 + 70 x 25 + 20 x 2 x 70 }\)
\(\text{= 70 x ( 35 + 25 + 40 )}\)
\(\text{= 70 x 100 = 7000 }\)
e) \(\text{5.3.37.4+5.24.21+21.5.12}\)
\(\text{= 5.(3.37.4+24.21+21.12)}\)
\(\text{= 5.1200}\)
\(=6000\)
1) 39×51+39×49=39x(51+49)=39x100=3900
2. phân tích 100 thành 50 r lm như câu 1
1. = 39 x (51 + 49)
= 39 x 100
= 3900
2. = 50 x 2 x 31 + 100 x 19
= 100 x 31 + 100 x 19
= 100 x (31 + 19)
= 100 x 50
= 5000
c: =53*55+53*145+53
=53*201
=10653
d: Số số hạng là (126-3):3+1=42(số)
Tổng là (126+3)*42/2=2709
7)
53.(51+4)+53.(49+96)+53
=53.55+53.145+53
=53.(55+145+1)
=53.201
=10653
8)
42.(15+96)+6.(25+4).7
=42.111+(6.7).29
=42.111+42.29
=42.(111+29)
=42.140
=5880
9)
45.(13+78)+9.(87+22).5
=45.91+(9.5).109
=45.91+45.109
=45.(91+109)
=45.200
=9000
10)
16.(27+75)+8.(53+25).2
=16.102+(8.2).78
=16.102+16.78
=16.(102+78)
=16.180
=2880
7)
53.(51+4)+53.(49+96)+53
=53.55+53.145+53
=53.(55+145+1)
=53.201
=10653
8)
42.(15+96)+6.(25+4).7
=42.111+(6.7).29
=42.111+42.29
=42.(111+29)
=42.140
=5880
9)
45.(13+78)+9.(87+22).5
=45.91+(9.5).109
=45.91+45.109
=45.(91+109)
=45.200
=9000
10)
16.(27+75)+8.(53+25).2
=16.102+(8.2).78
=16.102+16.78
=16.(102+78)
=16.180
=2880
Tính hợp lí
a,15.(27+ 18 +6 ) + 15.( 23 +12)
= 15(27+18+6+23+12)
= 15.86
= 1290
b,24.(15 + 49 ) + 12. ( 50 + 42 )
=12.2(15+49)+12.(50+42)
= 12(30+98)+12(50+42)
=12(30+98+50+42)
=12.220
= 2640
c,53.(51+4)+53.(49+96) +53
=53(51+4)+53(49+96)+53.1
=53(51+4+49+96+1)
=53.201
=10653
d,42.( 15 +96) +6.(25 +4).7
=42(15+96)+42(25+4)
=42(15+96+25+4)
=42.140
=5880
tick đúng cho mk nha pikachu
Đáp án
a) 714 + 382 + 286 + 318
= (714 + 286) + (382 + 318)
= 1000 + 700
= 1700
b) 125.98.2.8.25
= (125.2) . (98.25) . 8
= 250.2450.8
= 4900000
c) 78.31 + 78.24 + 22.17 + 22.38
= (78.31 + 78.24) + (22.17 + 22.38)
= 156.55 + 44.55
= 201.1
d) 53.(51+4) + 53.(49+95) + 53
= 53.55 + 53.144 + 53
= 53 x (55 + 144) + 53
= 55 x 199 + 53
= 10945 + 53
= 10998
a) 714 + 382 + 286 + 318
= (714 + 286) + (382 + 318)
= 1000 + 700
= 1700
b) 125.98.2.8.25
= (125.2) . (98.25) . 8
= 250.2450.8
= 4900000
c) 78.31 + 78.24 + 22.17 + 22.38
= (78.31 + 78.24) + (22.17 + 22.38)
= 156.55 + 44.55
= 201.1
d) 53.(51+4) + 53.(49+95) + 53
= 53.55 + 53.144 + 53
= 53 x (55 + 144) + 53
= 55 x 199 + 53
= 10945 + 53
= 10998