Japanese 101 - Adjective Conjugations (Finally!)

Here are the long promised adjective conjugations!
These are more informal, because I don't know the formal ones.

Adjectives are split into 2 groups, な, and い adjectives.
These two have different styles of conjugation.

 い always end with い.
With い adjectives;

-To put it into the present negative, replace ~い with ~くない
-To put it into the past, replace ~い with ~かった
-To put it into the past negative, replace ~い with ~くなかった

Example:

He isn't strong ;_;
あいつ が つよくない

He was strong
あいつ が つよかった

He was not strong
あいつ が つよくなかった

Easy isn't it?
There is one exception.
The adjective いい (Good)
It's conjugated as よい

So
よくない - Not good
よかった - Thats good (past)
よくなかった - Was not good


Now for な adjectives.
な adjectives don't always end in な, the only way to learn is to memorize which are which

We will use the word へん (strange) for this.

Lets start with the じゃconjugation
Negative past add ~ じゃありませんでした  to the adjective (as it is, don't add a な to it)
Negative add ~ じゃありません   to the adjective

 ~じゃない  is a more informal negative

Now the では Conjugation
Negative add ~ではありません
Past add ~でした
Negative past, add ~ではありませんでした

Examples:

Not strange
へんじゃありません　へんじゃない

Was Strange
へんじゃありませんでした

Not Strange
へんではありません

Was strange
へんではした

Wasn't strange
へんではありませんでした

Personally, the ~では sounds weird to me, as I am more use to using the ~じゃ