Question

"m=1/2"是"直线(m+2)x+3my+1=0与

Answer 1

如果垂直,那么(m+2)(m-2)+3m(m+2)=0m²-4+3m²+6m=04m²+6m-4=02m²+3m-2=0(2m-1)(m+2)=0m=1/2或m=-2所以m=1/2是直线(m+2)x+3my+1=0与直线(m-2)x+(m+2)y-3+0相互垂直的B充分不必要选B...