Question

31. Find f(x) = 3x + 4x2 + 5x + 9, find f (3).
OR​

Answer 1

Answer:

$f(x) = 4 {x}^{2} + 8x + 9$

$f(3) = 4 {(3)}^{2} + 8(3) + 9$

$= 4(9) + 8(3) + 9$

$36 + 24 + 9$

$= 69$

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Answer 2

The answer of this question as $f(3)=69$.

Step-by-step explanation:

We are given,

$f(x)=3x+4x^{2} +5x+9$

and we have to find the value of $f(3)$.

• Calculation for $f(3)$

we have ,

$f(x)=3x+4x^{2} +5x+9$

and we can write it as,

$f(x)=4x^{2} +8x+9$

For finding the value of $f(3)$ we put the value of x as 3, by putting 3 in place of x we get,

$f(x)=4x^{2} +8x+9$

$f(3)=4*(3)^{2} +8*(3)+9$

       $=4*9+24+9$

        $=36+24+9$

        $=69$

In this way we get the value of $f(3)$  as 69.