不定詞 分詞 が本当に区別がつかなくて苦手です。解説お願いします。

(① hegic入る適切な個または生殺を選択成ら選びなさい・ 口 1、 Please fnd me repor ofthe accident( )tOHhisemall ①⑩ attaching @⑥ attached ③to atach She was hurt by what you said、 would have been wiser for ou ( ④ attachment ) unsaid. 2) ① to leave ⑨bp be let ③tohaveleit ④tohaveleft ロ 3.Iheard aErenchsong( )byCathy. の⑩sung ⑨sing ⑧sang ⑨ singmg WW 口 4. The classroom was so noisy that the teacher couldnt makehersef( ). ①hear ⑨to hear ③ hearng ⑨⑳1heard 口 5 cannotbeleve whathetoldme. is( )tobetue. 〇ver good ②③ so good ⑧(too good ④ pretty good (WWA 口 6.( ) thc mowe before, jane didntwant to g0 to the theater with GS. ① Watched ぐ③ Having watcbed ⑧ Being watched ④ Haying been watched DO 口 7. She complained of the classroom( )toohot ④was dk ①being ②for being ⑧to be .( )by the smiles of the children in her clasS, Jane WaS happy with her frst day he dE new school. ①Delight @ Delightful ③Delighting ③④ Delighted <相内 口 9 Heregreted( )his house. ①⑪in seling ②havingsold ③jadsold ③④③to sel (東京学院 ) to have an operaton. ③ he will be necessary ④ it is necessary of him 口 10. The doctor says ( ① he js necessary ③ it is necessary for him ) we must have an eficient operation. 信剛科大 口 11. For production ( ①be increased ⑧ jncrease

2と3で判別式Dを使うのは理解できるんだけどなんでKの関数にして考えるっているのかがよくわからないです(>_<) それと2番は場合はわけしていないのはなぜですか？

この問題の解き方の解説をお願いします‼︎

実数解を持つかどうかはどこを見たらわかりますか？

(2)をお願いします‼︎

等差数列の問題です。 (1)がわからないです。 途中式お願いします！ <解答>初項-4 公差4