Someone please answer this for me I will give brainliest to person who explains

Aline passes through 3,7 and 6,9 what equation represents the line

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

Which function in vertex form is equivalent to f(x) = x2 + 6x + 3? f(x) = (x + 3)2 + 3 f(x) = (x + 3)2 − 6 f(x) = (x + 6)2 + 3 f(x) = (x + 6)2 − 6