Tính
2665 :[213-(17-9)]
78.31+78.24+78.17+22.72
3^6:3^2+2^3.2^2-(17-9)^2
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78.31+78.24+78.17+22.72
tính bằng 2 cách nha mk cần gấp
C1 : 78 . 31 + 78 . 24 + 78 . 17 + 22 . 72
= 78 ( 31 + 24 + 17 ) + 22 . 72
= 78 . 72 + 22 . 72
= ( 78 + 22 ) . 72
= 100 . 72
= 7200
C2 : 78 . 31 + 78 . 24 + 78 . 17 + 22 . 72
= 2418 + 1872 + 1326 + 1584
= 7200
\(78.31+78.24+78.17+22.72.\)
\(=78.\left(31+24+17\right)+22.72\)
\(=78.72+22.72\)
\(=72.\left(78+22\right)\)
\(=72.100=7200\)
C1:
78.31+78.24+78.17+22.72
= 78.(31+24+17)+22.72
= 78.72+22.72
= 72.(78+22)
=72.100
=7200
C2:
78.31+78.24+78.17+22.72
= 2418+78.24+78.17+22.72
= 2418+1872+78.17+22.72
= 2418+1872+1326+22.72
=2418+1872+1326+1584
= 4290+1326+1584
= 5616+1584
= 7200
tính:
a/ 1+7+8+15+23+...+160
b/ 1+4+5+9+14+...+60+97
c/78.31+78.24+78.17+22.72
Bạn chú ý dấu nhé Dấu (.) là nhân nha
__________________________
Tính:
a)1+7+8+15+23+...+160
b)1+4+5+9+14+...+60+97
c)78.31+78.24+78.17+22.72
a.1+7+8+15+23+...+160a.1+7+8+15+23+...+160
=1+(8−1)+(15−7)+(23−8)+...+(160−61)+(259−99)=1+(8−1)+(15−7)+(23−8)+...+(160−61)+(259−99)
=−7+160+259=−7+160+259
=412
Tính
a) 1 + 7 + 8 + 15 + 23 + ... + 160
b) 1 + 4 + 5 + 9 + 14 + ... + 60 + 97
c) 78.31 + 78.24 + 78.17 + 22.72
\(a.1+7+8+15+23+...+160\)
\(=1+\left(8-1\right)+\left(15-7\right)+\left(23-8\right)+...+\left(160-61\right)+\left(259-99\right)\)
\(=-7+160+259\)
\(=412\)
\(b.1+4+5+9+14+...+60+97\)
\(=1+4+5+9+14+23+37+60+97\)
\(=5+5+23+23+97+97\)
\(=2\left(5+23+97\right)\)
\(=2.125\)
\(=250\)
\(c.78.31+78.24+78.17+22.72\)
\(=78\left(31+24+17\right)+22.72\)\(=78.72+22.72\)\(=72\left(78+22\right)\)\(=72.100\)\(=7200\)Tính :
a} 1+7+8+15+23+...+160
b} 1+4+5+9+14+...+60+97
c} 78.31+78.24+78.17+22.72
Nói trước đay là toán nâng cao 6
c} 78.31+78.24+78.17+22.72
= 78.(31+24+17)+22.72
= 78.72+22.72
= 72.(78+22)
= 72 . 100
= 7200
b) 78.31+ 78.24+ 78.17+ 78.72
\(78\cdot31+78\cdot24+78\cdot17+78\cdot72\)
\(=78\left(31+24+17+72\right)\)
\(=78\cdot144=11232\)
=78.(31+24+17+72)
=78.144
=11232
78.31+78.24+78.17+22.72
tính bằng cách thuận tiện
Ta có: 78.31+78.24+78.17+22.72
= 78.(31 + 24 + 17) + 22.72
= 78 .72 + 22.72
= 72.(78 + 22)
= 72. 100
= 7200
= 78.(31+24+17)+22.72
= 78.72+22.72
= 72.(78+22)
= 72.100
= 7200
78.31+78.24+78.17+22.72 = ?
=78.(31+24+17)+22.72
=78.72+22.72
=72.(78+22)
=72.100
=7200
l.i.k.e mình nha ngo anh tu
78 . 31 + 78 . 24 + 78 . 17 + 22 . 72
= 78 . (31 + 24 + 17) + 72 . 22
= 78 . 72 + 72 . 22
= 72 . (78 + 22)
= 72 . 100
= 7200
TL:
78 . 31 + 78 . 24 + 78 . 17 + 22 . 72
= 78 . (31 + 24 + 17) + 72 . 22
= 78 . 72 + 72 . 22
= 72 . (78 + 22)
= 72 . 100
= 7200
HT
78.31+78.24+78.17+22.72 = ?
78.31+78.24+78.17+22.72
=78.(31+24+17)+22.72
=78.72+22.72
=72.(78+22)
=72.100
=7200
= 78.(31+24+17)+22.72
= 78.72+22.72
= 72.(78+22)
= 72.100
=7200