в какой особой форме глагола употреблюется суффиксы ущ ющ ащ ящ

при каком условии пишется ущ ющ а при каком ащ ящ

Решите уравнение

(х*6 - 956):4=70 

0,5 корень из 200 у - 0,2 корень из 162 у - корень из 242 у =???

Choose the correct word or phrase in each sentence

1 The teacher told/asked if I'd finished the test.

2 My mobile phone needs recharging! I wish the battery wasn't /isn't flat.

3  We showed round/were shown round the art gallery by our teacher.

4 If i won/win the lottery. I'd travel round the world.

5 I didn't know /wouldn't have known if you hadn't told me.

6 Rita left a message to say that she would join/had joined you in the pub tonight.

7 I said/told to Steve that I'd meet him at the swimming baths later.

8 If you'd done /you did more revision, you wouldn't have failed the exam.

9 I was giving/was given the necklace by my aunt.

10 I asked her if she would be/was from Switzerland, and she said no.

11I was here /I've been here since the beginning of June.

12 No,I can't see the bird. Where are you looking/do you look?

13  I'm going to tell her but I didn't see/I've not seen her yet.

14 I think we have time for a coffee before the train artives/will arrive.

15 When I was a baby I was carrying /I used to carry a yellow blanket everywhere I went.

Упростите выражение

[tex](\frac{2}{y}-\frac{y}{y^{2}+1})*\frac{3y}{y^{2}+2}[/tex]