Can someone please read that and give me an answer, i’ve been stuck on it for awhile.

Mathematics

1 answer:

olya-2409 [2.1K]3 years ago

4 0

Answer:

after 21 seconds

Step-by-step explanation:

Given

h = - 16t² + 272t + 1344

When the ball strikes the ground then h = 0, that is

- 16t² + 272t + 1344 = 0 ( divide through by - 16 )

t² - 17t - 84 = 0 ← in standard form

(t - 21)(t + 4) = 0 ← in factored form

Equate each factor to zero and solve for t

t - 21 = 0 ⇒ t = 21

t + 4 = 0 ⇒ t = - 4

However t > 0 thus t = 21

The ball strikes the ground after 21 seconds.

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Please help and good night

lana66690 [7]

Answer:

(7) n = ⁴/₃

(8) x = -5

(9) d = ³/₂

(10) v = -20

Step-by-step explanation:

(7) $n-\frac{8}{9} = \frac{4}{9}$

$n-\frac{8}{9} = \frac{4}{9} \\\\Collect \ similar \ terms \ together\\\\n = \frac{4}{9} + \frac{8}{9} \\\\n = \frac{4+8}{9} \\\\n = \frac{12}{9} \\\\n = \frac{4}{3}$

(8)

$\frac{3}{2} + \ x = -\frac{7}{2}\\\\collect \ similar \ terms \ together\\\\x = -\frac{7}{2} -\frac{3}{2} \\\\x = \frac{-7-3}{2} \\\\x = \frac{-10}{2} \\\\x = -5$

(9)

$\frac{6}{5} = \frac{d}{(\frac{5}{4} )} \\\\cross \ and \ multiply\\\\5d = 6(\frac{5}{4} )\\\\5d = \frac{30}{4} \\\\d = \frac{30}{4\times 5} \\\\d = \frac{30}{20} \\\\d = \frac{3}{2} \\\\d = 1\frac{1}{2}$