Bài 2:
a. $=58(75+50-25)=58.100=5800$
b. $=27.8+4.9-5=216+36-5=247$
Bài 3:
a.
$(x-38):16=12$
$x-38=16\times 12=192$
$x=192+38 = 230$
b.
$10+2x=4^5:4^3=4^2=16$
$2x=16-10=6$
$x=6:2=3$
c.
$440+2(125-x)=546$
$2(125-x)=546-440=106$
$125-x=106:2=53$
$x=125-53=72$
d.
$(x-15):5+20=22$
$(x-15):5=22-20=2$
$x-15=2\times 5=10$
$x=10+15=25$
e.
$2x-138=2^3.3^2=8.9=72$
$2x=72+138 = 210$
$x=210:2=105$
Bài 3:
f.
$2.3^x-5=7^2$
$2.3^x=7^2+5=54$
$3^x=54:2=27=3^3$
$\Rightarrow x=3$
g.
$7x-3^3=2^7:2^4$
$7x-27=2^3=8$
$7x=27+8=35$
$x=35:7=5$
h.
$427-(x+100)=227$
$x+100=427-227 = 200$
$x=200-100=100$
i.
$2x-138=2^3.3^2=8.9=72$
$2x=72+138 = 210$
$x=210:2=105$
k.
$(6x-18):3+25.2=78$
$(2x-6)+50=78$
$2x-6=78-50=28$
$2x=28+6=34$
$x=34:2=17$