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Mathematics

1 answer:

Degger [83]1 year ago

6 0

Solution:

Let x be the number of candles Kelly sold.

Let y be the number of candles Jakeya sold. Jakeya sold 5 more candles than Kelly;

$y=x+5$

Also, let z be the number of candles Cindi sold. Cindi sold 1 less than twice as many candles as Kelly.

$z=2x-1$

Altogether, they sold 52 candles;

$x+y+z=52$

Hence, the equation that could be used to determine the number of candles that Kelly sold is;

$x+x+5+2x-1=52$

CORRECT OPTION: B

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Answer: see proof below

<u>Step-by-step explanation:</u>

Given: A + B = C → A = C - B

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Use the Double Angle Identity: cos 2A = 2 cos² A - 1

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Use Even/Odd Identity: cos (-A) = cos (A)

<u>Proof LHS → RHS:</u>

LHS: cos² A + cos² B + cos² C

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$\text{Given:}\qquad \qquad 1+\cos C\cdot \cos (A-B)+\cos^2C$

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