What is the leading coefficient in 1-2x+5x^4 when in standard form

That's a lot of points for this question. You don't have to offer that much. 

Leading Coefficient: When written in standard form (starting with the variable with the highest power, going to the variable with the next highest power ... all the way down to a number with no variable), the leading coefficient is the number in front of the variable with the highest power. 

Let me put this less technically. Find the variable with the highest power. The number in front of that variable is the leading coefficient.

Write this in standard form. 5x^4 -2x + 1
The number in front of the x^4 is the answer.
5 <<<<< answer 

This is called the Pythagorean theorem : a ² + b ² = c ². You can substitute any of the variable with any of the known numbers and then you all you have to do is isolate the variable. I hope that helps!!