Bài 1:
x={21;49}
Bài 2:
a, 37.42+58.37-(88.21+12.21)
=37.(42+58)-21.(88+12)
=37.100-21.100
=3700-2100
=1600
b,$2020^{2021}$ :$2020^{2020}$ +[1080-(3.3$^{3}$ +999)
=2020+[1080-(81+999)
=2020+(1080-1080)
=2020+0
=2020
Bài 3:
a, 3x+27=162
3x =162-27
3x =75
x =75 : 3
x =25
b,$2^{x+7}$=2$^{2}$ .16+192
$2^{x+7}$ =64+192
$2^{x+7}$ =256
$2^{x+7}$ =2$^{8}$
x+7 =8
x =8-7
x =1
Bài 4 ; 5:
mik làm bài trong hình nhé