Question

À variable voltage in an electrical circuit is given by the formula V = t² - 20t+40. At which time after the circuit begins to function will the voltage be

6?
O 2.0 and 24.0 seconds
O 1.5 and 25.5 seconds
O 1.9 and 18.1 seconds

Answer 1

18.1 and 1.9

Explanation:

v(t) = t² -20t + 40

to find the voktage at a given time, set v(t) equal to voltage and solve for t.

use quadratic formula to solve.

6 = t² - 20t + 40

0 = t² -20t + 34

A = 1, B = -20, C = 30

insert for quad formula and solve