Evaluate Using the Given Value f(20) = square root of 5(20)-4

$f (20) = \sqrt{5 (20) - 4}$

Step 1

Multiply $5$ by $20$ .

$f (20) = \sqrt{100 - 4}$

Step 2

Subtract $4$ from $100$ .

$f (20) = \sqrt{96}$

Step 3

Rewrite $96$ as $4^{2} \cdot 6$ .

Factor $16$ out of $96$ .

$f (20) = \sqrt{16 (6)}$

Rewrite $16$ as $4^{2}$ .

$f (20) = \sqrt{4^{2} \cdot 6}$

Step 4

Pull terms out from under the radical.

$f (20) = 4 \sqrt{6}$