Can anyone help me?

Mathematics

1 answer:

suter [353]2 years ago

8 0

Answer:

0.8

Step-by-step explanation:

3(5x+2)+10=4

=15x+6+10=4

After this step you subtract 6 from each side and then subtract 10 from each side and then after that you divide 15x on each side which will give you 0.8.

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W(t)W, left parenthesis, t, right parenthesis models the daily water level (in \text{cm}cmstart text, c, m, end text) at a pond

erastovalidia [21]

Answer:

t=152 days (in radians)

Step-by-step explanation:

W(t)models the daily water level at a pond in Arizona, t days after the hottest day of the year. (t is entered in radian)

$W(t) = 15\cos\left(\dfrac{2\pi}{365}t\right) + 43$

We want to determine the first time,t at which the water level is 30cm.

When W(t)=30

$30 = 15\cos\left(\dfrac{2\pi}{365}t\right) + 43\\30-43=15\cos\left(\dfrac{2\pi}{365}t\right)\\-13=15\cos\left(\dfrac{2\pi}{365}t\right)\\-\dfrac{13}{15} =\cos\left(\dfrac{2\pi}{365}t\right)\\cos^{-1}(-\dfrac{13}{15})=\dfrac{2\pi}{365}t\right)\\cos^{-1}(\dfrac{13}{15})=\dfrac{2\pi}{365}t\right)$

$cos^{-1}(\dfrac{13}{15})=\dfrac{2\pi}{365}t\right)\\t=\dfrac{365}{2\pi}\cdot cos^{-1}(\dfrac{13}{15})\\t=152.16\\\approx 152 days \text{ (to the nearest whole day)}$