The leading coefficient is the constant (written in front) of the term or variable having the largest exponent.
To determine the leading coefficient, you have to determine the leading term first by arranging the terms from the term with the largest exponent to the term with the lowest exponent.
Therefore, the equation would look like this: f(x) = -1.4x^5 +3x^2 + 7x^2.
The leading term is -1.4x^5, therefore, the leading coefficient is -1.4