Justification for step 5 for her proof is combining like terms.
What are like terms and unlike terms ?
Like terms are terms that have the same variables and powers. The coefficients do not need to match. Unlike terms are two or more terms that are not like terms, i.e. they do not have the same variables or powers. The order of the variables does not matter unless there is a power.
According to the question
Darlene wrote this proof of the identity [tex](x+y)^2-(x-y)^2[/tex]=4xy.
In which
Step 5: [tex]x^{2} + 2xy + y^{2}[/tex] - [tex]x^{2} +2xy - y^{2}[/tex]= 4xy
like terms are added and subtracted
Hence, justification for step 5 for her proof is combining like terms.
To know more about like terms and unlike terms here:
https://brainly.com/question/2513478
#SPJ2
