Astudent is asked to calculate the value of 752 − 702 using the identity x2 − y2 = (x − y)(x + y). the student's steps are shown below.

step 1: 752 − 702 = (75 − 70)(75 + 70)

step 2: = (5)(155)

step 3: = (5)(150) + 5(5)

step 4: = 750 + 25

step 5: = 775

the correct answer should be 725. in which step did the student make his first error?
step 1
step 2
step 3