QUICK can anyone help me. Big points for right answers.

Mathematics

1 answer:

klemol [59]3 years ago

7 0

No13.
Answer:
Cos(x+x)=cosx*cosx-sinx*sinx
=cos2(x)-sin2(x)
=(cosx+sinx)(cosx-sinx)

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Two groups of staff at a store are making flowers to decorate the entrance. If Group A were to do it alone, it would take them 1

Tcecarenko [31]

Answer:

$\dfrac{6750}{7}$

Step-by-step explanation:

Let x be the number of flowers. If Group A were to make x flowers alone, it would take them 10 hours to complete the task, then they make $\dfrac{x}{10}$ flowers in an hour. If Group B were to make x flowers alone, it would take them 15 hours to complete the task, then they make $\dfrac{x}{15}$ flowers in an hour.

The groups decided to work together. They can make $\dfrac{x}{10}+\dfrac{x}{15}=\dfrac{x}{6}$ together in an hour and it takes them $\dfrac{x}{\frac{x}{6}}=6$ hours. Group B took a break for 1 hour and 40 minutes ( $1\dfrac{2}{3}$ hour), then Group B works

$6-1\dfrac{2}{3}=4\dfrac{1}{3}$ hours.

Thus,

$\dfrac{x}{10}\cdot 6-\dfrac{x}{15}\cdot 4\dfrac{1}{3}=300,\\ \\\dfrac{3x}{5}-\dfrac{13x}{45}=300,\\ \\14x=300\cdot 45=13500,\\ \\x=\dfrac{13500}{14}=\dfrac{6750}{7}.$