1.
a.=2/5^5+7/23+(-4/25)
=2/5^2×2/5^3+7/23+(-4/25)
=4/25×8/125+7/23+(-4/25)
={4/25+(-4/25}×8/125+7/23
=0×8/125+7/23
=0+7/23
=7/23
2.
a.(x-3/5)^2=4
(x-3/5)^2=2^2
x-3/5=2
x=2+3/5
x=13/5
Vậy...
b.2^x+2^x+3=144
=>2^x×1+2^x×2^3=144
=>2^x×(1+2^3)=144
=>2^x×9=144
=>2^x=144:9=16
=>x=4
Vậy ....
Câu bé bài 2 mk chx làm nha