1.次の放物線の焦点、準線を求めなさい。また、グラフも描きなさい。
(1)\(x^2=4y\)
\(x^2=4・y\)
焦点は\((0,1)\)
準線は\(y=-1\)
(2)\(y=-2x^2\)
\(\displaystyle x^2=4・\left(-\frac{1}{8}\right)y\)
焦点は\(\displaystyle \left(0,-\frac{1}{8}\right)\)
準線は\(\displaystyle y=\frac{1}{8}\)
(3)\(y^2=8x\)
\(\displaystyle y^2=4・2x\)
焦点は\((2,0)\)
準線は\(x=-2\)
(4)\(y^2=-4x\)
\(\displaystyle y^2=4・-x\)
焦点は\((-1,0)\)
準線は\(x=1\)
(5)\(y^2=x\)
\(\displaystyle y^2=4・\frac{1}{4}x\)
焦点は\(\displaystyle \left(\frac{1}{4},0\right)\)
準線は\(\displaystyle x=-\frac{1}{4}\)