Can you please solve both algebra and calculus questions (all questions) the questions are via attachment

Question

can you please solve both algebra and calculus questions (all questions).the questions are via attachment.

Switch to polar coordinates:
cos3 θ − sin3 θ
x3 − y 3
r3 cos3 θ − r3 sin3 θ
=
lim
r
·
= 0
=
lim
r→0
r→0 r 2 cos2 θ + r 2 cos θ sin θ + r 2 sin2 θ
(x,y)→(0,0) x2 + xy + y 2
1 +…
Math