A ball is thrown into the air with an initial upward velocity of 46 ft/s. Its height (h) in feet after t seconds is given by the function h=-16t^2 +46t +6. After how many seconds will the ball hit the ground?
A. 3
B. 4
C. 5
D. 6
I am at this part:-16t^2 +46t +6=0
I dont know how to factor this....can someone plz help me
26 answers
why factor? Just use the quadratic formula. It always works.
-16t^2 +46t +6=0
is the sameas
16 t^2 - 46 t - 6 = 0
which is
8 t^2 - 23 t - 3 = 0
now factor
is the sameas
16 t^2 - 46 t - 6 = 0
which is
8 t^2 - 23 t - 3 = 0
now factor
right off you can see
need
( something - 3)(something + 1)
or
(something +3 )(something -1)
need
( something - 3)(something + 1)
or
(something +3 )(something -1)
so try (t-3)( something t + 1)
the quadratic equation means
if
a x^2 + b x + c = 0
then
x = [ -b +/- sqrt (b^2 - 4 a c) ]/ (2a)
if
a x^2 + b x + c = 0
then
x = [ -b +/- sqrt (b^2 - 4 a c) ]/ (2a)
You can get it by completing the square
a x^2 + b x = -c
x^2 + (b/a) x = -c/a
x^2 + (b/a) x + (b / 2a)^2 = -c/a + (b / 2a)^2
(x+ b/2a)^2 = -c/a + (b / 2a)^2
x+ b/2a = +/- sqrt (-c/a+b^2/4a^2)
x = -b/2a +/- sqrt [ (- 4 c a + b^2 )/4 a^2 ]
= -b/2a +/- (1/2a)sqrt (b^2 - 4 a c)
= [ -b +/- sqrt(b^2 - 4ac) ] / 2a
a x^2 + b x = -c
x^2 + (b/a) x = -c/a
x^2 + (b/a) x + (b / 2a)^2 = -c/a + (b / 2a)^2
(x+ b/2a)^2 = -c/a + (b / 2a)^2
x+ b/2a = +/- sqrt (-c/a+b^2/4a^2)
x = -b/2a +/- sqrt [ (- 4 c a + b^2 )/4 a^2 ]
= -b/2a +/- (1/2a)sqrt (b^2 - 4 a c)
= [ -b +/- sqrt(b^2 - 4ac) ] / 2a
V = Vo + g*Tr = 0
46 - 32Tr = 0
Tr = 1.44 s. = Rise time.
V^2 = Vo^2 + 2g*h1 = 0
46^2 - 64h1 = 0
h1 = 33 ft. above launching point.
h = 33+6 = 39 ft. above gnd.
16Tf^2 = 39
Tf = 1.56 s. = Fall time.
Tr+Tf = 1.44 + 1.56 = 3 s. to hit gnd.
46 - 32Tr = 0
Tr = 1.44 s. = Rise time.
V^2 = Vo^2 + 2g*h1 = 0
46^2 - 64h1 = 0
h1 = 33 ft. above launching point.
h = 33+6 = 39 ft. above gnd.
16Tf^2 = 39
Tf = 1.56 s. = Fall time.
Tr+Tf = 1.44 + 1.56 = 3 s. to hit gnd.
so the answer?
3 seconds?
hello??? answers pleaseee
actually i got y’all:
b
a
a
c
d
c
c
a
b
a
a
c
d
c
c
a
kabutos admirer is 100% correct!
yea kabutos admirer is correct 😄👍🏼.
kabutos admirer is a life saver <3
Kabutos admirer really is a life saver. XD Those are still the correct answers as of today!
I've been looking up quadratic formulas and everything but oml these word problems suck </3
(the only reason i made it through the blanket in the practice one was acting like it was a riddle and not doing any math </3)
(the only reason i made it through the blanket in the practice one was acting like it was a riddle and not doing any math </3)
thank you soooosoo much everyone especially kabutos admirer!! have a great day everyone!! :3
Update! I took the quiz and I got 4/8. I guess they changed the answers :/
The new ones are:
b
a
c
d
c
c
b
a
good luck guys!
The new ones are:
b
a
c
d
c
c
b
a
good luck guys!
I just took it and the answers only changed slightly
1.) B | (1,3)
2.) A | Maximum
3.) A | 3
4.) C | 42 feet
5.) D | 11, -11
6.) C | -7,-1
7.) C | -6,4
8.) A | 3.33 ft
There y'all go- I wouldn't have spent so long typing that if it was wrong LSDFHK good luck fellow cheaters ^^
1.) B | (1,3)
2.) A | Maximum
3.) A | 3
4.) C | 42 feet
5.) D | 11, -11
6.) C | -7,-1
7.) C | -6,4
8.) A | 3.33 ft
There y'all go- I wouldn't have spent so long typing that if it was wrong LSDFHK good luck fellow cheaters ^^
omg TYSM SukunaIsMyHusbando!
karaboutos is still correct as of april 28 2021
Kabutos is correct as of now
SukunaIsMyHusbando is correct, I hot 8/8 thank you
Kabuto is right! Their a life saver 100% correct! ❤❤
Kabuto still 100%
@ SukunaIsMyHusbando is still correct has of 2023 lol