[微積] tangent line

[ytyt5239 (ytyt)]

Draw a diagram to show that there are two tangent lines to the parabola y=x平方
that pass through the point (0,-4).Find the coordinates of the points where
these tangent lines intersect the parabola.
我只找到斜率設一個直線方程式就不知道幹嘛了~哭哭

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→ CaptainH    :(0,-4)不在曲線上 => 假設切點(t,t^2), 計算兩點斜率
→ CaptainH    :就能解t了
→ ytyt5239    :Iget it. thx^^