Đáp án:
Giải thích các bước giải:
Bài1
a)369-(|-206|-15)-(-206+|-369|)
=369-(206-15)-(-206+369)
=369-206+15+206-369
=(369-369)+(-206+296)+15
=0+0+15
=15
b)345-150÷[(3^3-24)^2-(-21)]+2018^0
=345-150÷[(27-24)^2+21]+1
=345-150÷[3^2+21]+1
=345-150÷[9+21]+1
=345-150÷30+1
=345-5+1
=340+1
=341
c)-2+8-12+18-....-92+98
=6+6+6+6+6+6+6+6+6+6
=10.6
=60
Bài 2
a)20-[4^2+(x-6)]=90
20-[16+(x-6)]=90
16+(x-6)=20-90
16+(x-6)=-70
x-6 =16-(-70)
x-6=16+70
x-6=86
x=86+6
x=92
b)24-|x+8|=3.(2^5-5^2)
24-|x+8|=3.(32-25)
24-|x+8|=3.7
24-|x+8|=21
|x+8|=24-21
|x+8|=3
->x+8=3 hoặc x+8=-3
* x+8=3. | *x+8=-3
x=3-8. | x=-3-8
x=-5. | x=-11
Vậy x=-5 hoặc x=-11
c)1000÷[30+(2^x-6)]=3^2+4^2
1000÷[30+(2^x-6)]=9+16
1000÷[30+(2^x-6)]=25
30+(2^x-6)=1000÷25
30+(2^x-6)=40
2^x-6=40-30
2^x-6=10
2^x=10+6
2^x=16
2^x=2^4
--> x=4