Please help me with #2! Thanks!!!
1 answer:
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Answer:
The pebble will hit the ground 8.29 second after it is thrown.
Step-by-step explanation:
Given that,
The height of the pebble after t seconds is given by the equation
h= -16t²+24 t+900.
When the pebble hit the ground, the height of the pebble will be zero.
So putting h=0 in the given equation.
0 = -16t²+24 t+900
⇒-4(4t²-6t-225)=0
⇒4t²-6t-225=0
Applying quadratic formula , here a=4, b= -6 and c= -225.
⇒ t = 8.29, -6.79
Since time can not negative.
∴t=8.29 seconds.
The pebble will hit the ground 8.29 second after it is thrown.
Answer:
(-∞, -2), (-2, -0.618), and (1.618, 3)
Step-by-step explanation:
The red arrows indicate the regions in which the function is decreasing.
The corresponding intervals are (-∞, -0.618) and (1.618, 3),
Let's examine the intervals given.
(-∞, -2): Yes, decreasing.
(-2, -0.618): Yes, decreasing.
(-2, 0.689): No. Decreasing in (-2, -0.618) but increasing in (-0.618, 0.689).
(-1.17, 0.689): No. Decreasing in (-1.17, -0.618) but increasing
in (-0.618, 0.689).
(0.698, 71.457): No. Increasing from (0.698, 1.618), decreasing in (1.618, 3) and increasing in (3, 71.457).
(1.618, 3): Yes, decreasing.
(2.481, ∞): No. Decreasing in (2.481, 3) but increasing in (3, ∞).
The three choices that indicate a decreasing interval are (-∞, -2),
(-2, -0.618), and (1.618, 3).
