f(x)=9(x+16)^2+13 Find f(3a+9)=

Question

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Answer 1

f(x) = 9(x+16)^2 + 13

replace x by 3a+9

f(3a+9)^2 = 9((3a+9+16)^2+13

= 9(3a+25)^2 +13

= 9(9a^2 +150a + 625) +13

= 81a^2 + 1350a + 5625 +13

f(3a+9) =81a^2 +1350a + 5638