1.
a.
\(\left(-3\right).\left(-15\right).20.\left(-4\right)\\ =45.40.\left(-4\right)\\ =1800.\left(-4\right)=-7200\)
b.
\(21.\left(-12\right).\left(-11\right)\\ =21.132\\ =2772\)
c.
\(\left(-2\right)^2.\left(-3\right)^3.\left(-4\right)\\ =4.\left(-27\right).\left(-4\right)\\ =4.108=432\)
2.
a.
\(21.27+21.37\\ =21\left(27+37\right)\\ =21.64\\ =1344\)
b.
\(\left(-101\right).99-101.101\\ =\left(-101\right)\left(99+101\right)\\ =-101.200\\ =-20200\)
c.
\(52.54-154.52\\ =52\left(54-154\right)\\ =52.\left(-100\right)=-5200\)
3.
a.
\(\left|1-2x\right|=5\\ \Rightarrow\left[{}\begin{matrix}1-2x=5\\1-2x=-5\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-2\\x=3\end{matrix}\right.\)
b.
Nếu x>=0
\(\Rightarrow x+2x=6\\ \Rightarrow3x=6\\ \Rightarrow x=2\left(TM\right)\)
Nếu x<0
\(-x-2x=6\\ \Rightarrow-3x=6\\ \Rightarrow x=-2\left(TM\right)\)
4.
\(5^x=625\\ \Rightarrow5^x=5^4\\ \Rightarrow x=4\)
bài 1
a,(-3).(-15).(20).(-4)
=[(-3).(-15).(-4)].20
=(-180).20
= -3600
b,21.(-12).(-11)
=[(-12).(-11)].21
=132.21
=2772
c,(-2)2.(-3)3.(-4)
=4.(-27).(-4)
=[(-27).(-4)].4
=108.4
=432
bài 2
a, 21.27.21.37
=212.(27.37)
=441.999
=440559
b,(-101).99-101.101
= [(-101).99]-(101.101)
=(-9999)-10201
= -20200
c,52.54-154.52
=52.(54-154)
=52.(-100)
= -5200
bài 4
5x=625
5x=54
=>x=4
vậy x=4
