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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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
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
\(a.1+7+8+15+23+...+160\)
\(=1+\left(8-1\right)+\left(15-7\right)+\left(23-8\right)+...+\left(160-61\right)+\left(259-99\right)\)
\(=-7+160+259\)
\(=412\)
\(b.1+4+5+9+14+...+60+97\)
\(=1+4+5+9+14+23+37+60+97\)
\(=5+5+23+23+97+97\)
\(=2\left(5+23+97\right)\)
\(=2.125\)
\(=250\)
c} 78.31+78.24+78.17+22.72
= 78.(31+24+17)+22.72
= 78.72+22.72
= 72.(78+22)
= 72 . 100
= 7200
\(78\cdot31+78\cdot24+78\cdot17+78\cdot72\)
\(=78\left(31+24+17+72\right)\)
\(=78\cdot144=11232\)
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
l.i.k.e mình nha ngo anh tu
78.31+78.24+78.17+22.72
=78.(31+24+17)+22.72
=78.72+22.72
=72.(78+22)
=72.100
=7200