The correct representation are as follows:
Part (a): 
Part (b): 
Part (c): 
Part (d): 
Part (e): 
Further explanation:
in the question it is given that while writing any mathematical expression the symbol to be used for multiplication is
.
For example:
is incorrect and
is correct.
If a mathematical expression is to be written in its explicit form then the symbol
is used.
Part (a):
The expression given in part (a) is as follows:

The correct representation of the above expression is as follows:

For multiplication
symbol is used.
Part (b):
The expression given in part (b) is as follows:

The correct representation of the above expression is as follows:

For multiplication
symbol is used.
Part (c):
The expression given in part (c) is as follows:

The correct representation of the above expression is as follows:

Part (d):
The expression given in part (d) is as follows:

The correct representation of the above expression is as follows:

For multiplication
symbol is used.
Part (e):
The expression given in part (e) is as follows:

The correct representation of the above expression is as follows:

For multiplication
symbol is used.
Learn more:
1. A problem on greatest integer function brainly.com/question/8243712
2. A problem to find radius and center of circle brainly.com/question/9510228
3. A problem to determine intercepts of a line brainly.com/question/1332667
Answer details:
Grade: College
Subject: Mathematics
Chapter: NA
Keywords: Expression, representation, ma, cdot, aestrick, wcos(2theta)-1, asin(x)+15, sqraureroot(2gdeltay/m), N0e-lamda t, lowercase greek, multiplication dot.