Yes, that is a legal play.
As long as your tiles are all in a single row/column and form a single word it's a legal play. This question explains this further.
Your play is a very common technique to get extra points. The linked to answers in the comments are examples of similar plays that get many extra points. As @jolenealaska says, it was a very good ...
This is really just an expansion on LeppyR64's answer, which is correct: the move is legal.
Whether any word formed by a legal move is valid under the agreed-upon dictionary is a separate matter. It is perfectly legal to make up a word. It's the responsibility of an opponent to challenge a play under Rule #8 of the official rules if they believe a word ...
As explained in the other answers, the general pattern is fine. I frequently make 50+ point plays this way (6 x 8 + a few extra - (With X there is EX, AX, XI, XU, with J there is JO), even more occasionally with QI or ZA (6 x 10 + a few extra).
However, according to the online official dictionary, EA is not a valid word. Some other dictionaries may ...
That is legal, if ax and ea are valid words.
When you place tiles alongside another word on the board, every single new combination of letters that is formed must also be valid words and are counted for points.
(Image cropped from https://img.wonderhowto.com/img/91/78/63406678713167/0/master-scrabble-win-every-game.w1456.jpg)
Imagine AXION was just played. ...
This is a perfectly legal move covered by the third point in the rules excerpt below.
New words may be formed by:
Adding one or more letters to a word or letters already on the board.
Placing a word at right angles to a word already on the board. The new word must use one of the letters already on the board or must ...