x & gt 1，x+ 1/2x & gt； 2 ? What is the opposite of? x = & lt 1，x+ 1/2x = & lt； 2 ?

According to x 2 = 2py, we can know that the directrix equation of p= 1/2 is y=-(p/2), that is, x= 1/4.

√(a & amp； # 178; +b & amp； # 178; )/a=3√6/6

This is neither sufficient nor necessary.

6. Insufficient necessity

7. asymptote equation is y=-b/a? b/a=2？ c=√5a？ (c, 0) On the straight line y=-2x+5, if c=√5, then a= 1 b=2.