Answer:
r²+6r+9
Step-by-step explanation:
for the expansion of (r+3)², we use the formula as,
(a+b)²=a²+2ab+b²
here, we have
a=r
b=3
plug in all the values
(r+3)²=r²+2(r)(3)+3²
solving the equation
(r+3)²=r²+6r+9
