Bài 7:
a: \(\left(-12\right)\cdot8=-96;\left(-19\right)\cdot3=-57\)
mà -96<-57
nên \(\left(-12\right)\cdot8< \left(-19\right)\cdot3\)
b: \(11\cdot\left(-2\right)=-22;\left(-3\right)\cdot10=-30\)
mà -22>-30
nên \(11\cdot\left(-2\right)>\left(-3\right)\cdot10\)
c: \(\left(-16\right)\cdot10=-160;\left(-32\right)\cdot11=-352\)
mà -160>-352
nên \(\left(-16\right)\cdot10>\left(-32\right)\cdot11\)
d: \(\left(-17\right)\cdot3=-51;\left(-22\right)\cdot2=-44\)
mà -51<-44
nên \(\left(-17\right)\cdot3< \left(-22\right)\cdot2\)
Bài 8:
a: \(-64+8\left(77-19\right)\)
\(=-8\cdot8+8\cdot58\)
\(=8\cdot50=400\)
b: \(128\left(278-302\right)+278\left(302-128\right)\)
\(=128\cdot278-128\cdot302+278\cdot302-278\cdot128\)
\(=-128\cdot302+278\cdot302=302\cdot\left(278-128\right)\)
\(=302\cdot150=45300\)
c: \(\left(-8\right)\cdot7\cdot\left(-3\right)\cdot\left(-5\right)\)
\(=-8\cdot7\cdot3\cdot5\)
\(=-3\cdot7\cdot8\cdot5=-21\cdot40=-840\)
d: \(2\cdot\left(-7\right)^2+3\cdot\left(-4\right)^3-60\)
\(=2\cdot49+3\cdot\left(-64\right)-60\)
=98-192-60
=-154
