\(\)1)A={xEN*/x\(\ge\)6}
2) a)\(\Rightarrow\left(x+15\right).9=45\)
\(\Rightarrow x+15=45:9=5\)
\(\Rightarrow x=5-15\)
\(\Rightarrow x=-10\)
b) \(\Rightarrow10+2x=20\)
\(\Rightarrow2x=20-10=10\)
\(\Rightarrow x=10:2=5\)
tíc mình nha
bai 1a ban viet duoi dang liet ke nha ! cam on nhieu!