P(x+3)= [2(x+3)3]+[11(x+3)2]+[16(x+3)6]
P(x+3)=(6x+18)+(22x+66)+(96x+288)
P(x+3)=(6x+22x+96x)+(18+66+288)
P(x+3)=124x+372
What I did in the above solution is substitute the value of x which is x+3 to all the x's on the right of the equation and perform the math operations.