If $f (x) = 2 x^{2} - x$ $f(x) = 2x^2- x$ , what is f(-3)?

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If $f (x) = 2 x^{2} - x$ $f(x) = 2x^2- x$ , what is f(-3)?

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Answer 1 · 2016-08-13T13:48:16

$f (- 3) = 21$ $f(-3)=21$

Explanation:

To evaluate f( -3) substitute x = - 3 into f(x)

$\Rightarrow f (- 3) = 2 {(- 3)}^{2} - (- 3)$ $rArrf(color(red)(-3))=2(color(red)(-3))^2-(color(red)(-3))$

$= (2 \times 9) + 3 = 21$ $=(2xx9)+3=21$

Answer 2 · 2016-08-13T13:51:13

$f (- 3) = 21$ $f(-3)=21$

Explanation:

For any function $f (x)$ $f(x)$ to find $f (a)$ $f(a)$ for a constant number $a$ $a$ , we have just put $x = a$ $x=a$ in $f (x)$ $f(x)$ and we get $f (a)$ $f(a)$ .

As $f (x) = 2 x^{2} - x$ $f(x)=2x^2-x$ ,

$f (- 3) = 2 \times {(- 3)}^{2} - (- 3)$ $f(-3)=2×(-3)^2-(-3)$

= $2 \times 9 + 3$ $2×9+3$

= $18 + 3 = 21$ $18+3=21$

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If $f (x) = 2 x^{2} - x$ $f(x) = 2x^2- x$ , what is f(-3)?

2 Answers

Explanation:

Explanation:

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If $f (x) = 2 x^{2} - x$ $f(x) = 2x^2- x$ , what is f(-3)?