F(x) = — 3х2 – 6х +5 maximum and minimum value
1 answer:
9514 1404 393
Answer:
maximum: 8; no minimum
Step-by-step explanation:
A graph can be useful. I find a graphing calculator handy. It shows the maximum of the function is f(-1) = 8. Since the parabola goes to -∞ for large values of x, there is no minimum.
maximum: 8
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You can also find the maximum by putting the function in vertex form.
-3(x^2 +2x) +5 . . . . factor the leading coefficient from the x terms
-3(x^2 +2x +1) +5 -(-3)(1) . . . . add the square of half the x-coefficient, subtract the equivalent amount
-3(x +1)^2 +8 . . . . . . the vertex form of the expression for f(x)
This form is ...
a(x -h)^2 +k . . . . . with a=-3, h=-1, k=8
so the vertex is (h, k) = (-1, 8) -- the same as shown on the graph. The negative value of 'a' tells you the parabola opens downward, so the vertex is the maximum. The maximum is 8 at x = -1.
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Answer:
a) t = 4000/v
b) t = 4000/(v + 20)
c) see attached workings
Step-by-step explanation:
a) A man jogs 4 km everyday at an average speed of v m/min
As the speed is measured in <u>meters per minute</u>, we need to convert the distance (4 km) into meters:
1 km = 1000 m
⇒ 4 km = 4 x 1000 = 4000 m
distance = speed x time
⇒ time = distance / speed
⇒ t = 4000/v (where t = time in minutes)
b) If his average speed increased by 20 m/min, then his speed would now be (v + 20) m/min
⇒ t = 4000/(v + 20) (where t = time in minutes)
c) Given the man would take 3 min less if his average speed increased by 20 m/min, we can rewrite the second equation as:
t - 3 = 4000/(v + 20)
Now simply substitute the first equation t = 4000/v into the second:
(I have typed this used MS Word and attached, as the equation editor here in Brainly is not working at the moment).
