Question

If f(x) = 3x2 – 7, what is the value of f(-2)

Answer 1

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We have to find the value of f(-2) so we must place x = -2 in f(x) equation to get our required answer.

By Solving & simplifying we get,

`:\implies\sf{f(-2) = 3 {x}^(2) - 7}`

`:\implies\sf{f(-2) = 3 {( - 2)}^(2) - 7}`

`:\implies\sf{f(-2) = 3 * 4 - 7}`

`:\implies\sf{f(-2) = 12 - 7}`

`:\implies\sf{f(-2) = 5}`

• The value of f(-2) is 5.

Answer 2

f(-2) = 5

Explanation:

Put the value where the variable is, and do the arithmetic.

f(-2) = 3(-2)² -7 = 3(4) -7

f(-2) = 5