Question

F(x)=3x 2+x Find f(−5)

Answer 1

$\huge \boxed{\mathfrak{Question} \downarrow}$

• f (x) = 3x² + x
• Find f (-5).

$\large \boxed{\mathfrak{Answer \: with \: Explanation} \downarrow}$

Given,

• f (x) = 3x² + x

Now, we have to find f (-5). To find this, we just need to substitute -5 in the place of x.

So,

$\sf \: f(x) = {3x}^{2} + x \\ \\ \sf \: \: Substitute \: x \: as \: - 5. \\ \\ \sf \:f( - 5) = 3( - 5) ^{2} + ( - 5) \\ \\ \sf \:Calculate \: -5 \: to \: the \: power \: of \: 2 \: and \: get \: 25. \\ \\\sf \: 3\times 25+5 \\ \\ \sf \:Multiply \: 3 \: and \: 25 \: to \: get \: 75. \\ \\\sf \: 75+5 \\ \\\sf \:Add \: 75 \: and \: 5 \: to \: get \: 80. \\ \\ = \boxed{\boxed{ \bf \: 80}}$