Question

Consider � (�) = � 2 - 14 � - 7 f (t) = t 2 −14t - 7f, left parenthesis, t, right parenthesis, equals, t, mulus, 14, t, minus, 7 a function which corresponds to the path of a mobile object according to time. In what instant (s) is the furniture in position 8 88?

Answer 1

There are two moments where the object is in position 8: in t = 15 and t = -1.

To find the moment when object is at position 8 , just match the (t) a function A 8 and resolve to t . First, we subtracted 8 on both sides of the equation to put it in standard form:

t² - 14t - 15 = 0

Now we can use a quadratic formula to solve:

t = (-b ± √ (b² - 4ac))/(2a)

Replacing the values ​​of A, B and C, we get:

t = (-(-14) ± √ ((-14) ²-4 (1) (-15)))) / (1 (1 ))

t = (14 ± √256)/2

t = (14 ± 16)/2

< /P>