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lisabon 2012 [21]

2 years ago

10

A cab company calculates cab fares using the expression 1.50d + 3, where d is the distance traveled in miles. If a passenger has

to pay a $21 fare for a ride, which number from the set {9, 12, 15, 18} is the value of d?

1 answer:

Dovator [93]2 years ago

5 0

Answer:

12

Step-by-step explanation:

⇒ 21 - 3 = 18 = 1.5a

⇒ a = 12

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Jeff has to pay his car insurance annually. If his total bill is $744, how much money should he set aside each month for car ins

daser333 [38]

<span>Since Jeff is paying an annual amount of $744 he needs to set aside 12 monthly payments for the year. To figure out how much each payment would be you divide the total for the year 744 by the number of months 12. $744/12=$62 Each monthly payment would be $62</span>

7 0

3 years ago

Prove that: (b²-c²/a)CosA+(c²-a²/b)CosB+(a²-b²/c)CosC = 0

IRISSAK [1]

<u>Prove that:</u>

$\:\:\sf\:\:\left(\dfrac{b^2-c^2}{a}\right)\cos A+\left(\dfrac{c^2-a^2}{b}\right)\cos B +\left(\dfrac{a^2-b^2}{c}\right)\cos C=0$

<u>Proof: </u>

We know that, by Law of Cosines,

$\sf \cos A=\dfrac{b^2+c^2-a^2}{2bc}$
$\sf \cos B=\dfrac{c^2+a^2-b^2}{2ca}$
$\sf \cos C=\dfrac{a^2+b^2-c^2}{2ab}$

<u>Taking</u><u> </u><u>LHS</u>

$\left(\dfrac{b^2-c^2}{a}\right)\cos A+\left(\dfrac{c^2-a^2}{b}\right)\cos B +\left(\dfrac{a^2-b^2}{c}\right)\cos C$

<em>Substituting</em> the value of <em>cos A, cos B and cos C,</em>

$\longmapsto\left(\dfrac{b^2-c^2}{a}\right)\left(\dfrac{b^2+c^2-a^2}{2bc}\right)+\left(\dfrac{c^2-a^2}{b}\right)\left(\dfrac{c^2+a^2-b^2}{2ca}\right)+\left(\dfrac{a^2-b^2}{c}\right)\left(\dfrac{a^2+b^2-c^2}{2ab}\right)$

$\longmapsto\left(\dfrac{(b^2-c^2)(b^2+c^2-a^2)}{2abc}\right)+\left(\dfrac{(c^2-a^2)(c^2+a^2-b^2)}{2abc}\right)+\left(\dfrac{(a^2-b^2)(a^2+b^2-c^2)}{2abc}\right)$

$\longmapsto\left(\dfrac{(b^2-c^2)(b^2+c^2)-(b^2-c^2)(a^2)}{2abc}\right)+\left(\dfrac{(c^2-a^2)(c^2+a^2)-(c^2-a^2)(b^2)}{2abc}\right)+\left(\dfrac{(a^2-b^2)(a^2+b^2)-(a^2-b^2)(c^2)}{2abc}\right)$

$\longmapsto\left(\dfrac{(b^4-c^4)-(a^2b^2-a^2c^2)}{2abc}\right)+\left(\dfrac{(c^4-a^4)-(b^2c^2-a^2b^2)}{2abc}\right)+\left(\dfrac{(a^4-b^4)-(a^2c^2-b^2c^2)}{2abc}\right)$

$\longmapsto\dfrac{b^4-c^4-a^2b^2+a^2c^2}{2abc}+\dfrac{c^4-a^4-b^2c^2+a^2b^2}{2abc}+\dfrac{a^4-b^4-a^2c^2+b^2c^2}{2abc}$

<em>On combining the fractions,</em>

$\longmapsto\dfrac{(b^4-c^4-a^2b^2+a^2c^2)+(c^4-a^4-b^2c^2+a^2b^2)+(a^4-b^4-a^2c^2+b^2c^2)}{2abc}$

$\longmapsto\dfrac{b^4-c^4-a^2b^2+a^2c^2+c^4-a^4-b^2c^2+a^2b^2+a^4-b^4-a^2c^2+b^2c^2}{2abc}$

<em>Regrouping the terms,</em>

$\longmapsto\dfrac{(a^4-a^4)+(b^4-b^4)+(c^4-c^4)+(a^2b^2-a^2b^2)+(b^2c^2-b^2c^2)+(a^2c^2-a^2c^2)}{2abc}$

$\longmapsto\dfrac{(0)+(0)+(0)+(0)+(0)+(0)}{2abc}$

$\longmapsto\dfrac{0}{2abc}$

$\longmapsto\bf 0=RHS$

LHS = RHS proved.

7 0

2 years ago

Roberto watched 5 more hours of tv than Jamie last week. Together, they watched a total of 23 hours of tv last week. How many ho

Veronika [31]

Answer: 14 hours

Step-by-step explanation:

Let the number of hours of TV that Jamie watched be represented by x.

Since Roberto watched 5 more hours of tv than Jamie last week, therefore the number of hours of TV that Roberto watched will be: x + 5

Together, they watched a total of 23 hours of tv last week. Therefore,

x + (x + 5) = 23

2x + 5 = 23

2x = 23 - 5

2x = 18

x = 18/2

x = 9

Jamie watched 9 hours of TV

Therefore, Roberto watched x+ 5 = 9 + 5 = 14 hours

3 0

2 years ago

(08.05, 08.06 MC)

natali 33 [55]

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7 0

1 year ago

Is 19.1 the same as 191

laiz [17]

Answer:

no

Step-by-step explanation:

6 0

3 years ago