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Morgarella [4.7K]
4 years ago
15

Solve the equation by completing the square. x^2 -2x = 15

Mathematics
1 answer:
dlinn [17]4 years ago
5 0

Answer:

x = -3  or  x = 5

Step-by-step explanation:

Solve:   x^2 -2x = 15

x^2  - 2x  - 15 = 0

Use the Diamond method of factoring

-15 = 3* -5  and  3 - 5 = -2  so...

x^2  - 2x  - 15 = x^2 -  5x  + 3x  -  15

x^2  - 2x  - 15 = x *(x - 5)  + 3*(x - 5)

x^2  - 2x  - 15 = (x  + 3)*(x - 5)

x^2  - 2x  - 15 = (x  + 3)*(x - 5)  = 0

solve  (x + 3 ) = 0  and  (x - 5) = 0

x = -3  or  x = 5

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Step-by-step explanation:

the area of a circle (all 360°) is

pi×r²

with r being the radius.

the area of a circle segment is just the corresponding fraction of the whole circle.

so the area of a segment of x degrees is

pi×r² × x/360

in our case we know

pi×42240² × x/360 = 180 mi²

we also know that there are 5280 ft in 1 mile.

so, the radius is actually

42240 / 5280 = 8 miles

and therefore our equation resulting in mi² has to use miles and not ft and has to look that way :

pi×8² × x/360 = 180 mi²

pi×64 × x/360 = 180

pi×64 × x = 180×360

pi×x = 180×360/64 = 1012.5

x = 1012.5/pi = 322.2887598...°

so, the angle of the segment of a circle with the area of 180 mi² and the radius of 8 mi is 322.2887598...°

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2 years ago
Philip and Kevin are hoping to earn enough money to buy concert tickets for a show that costs $225 her concert tickets. Philip a
Zigmanuir [339]

Answer:

Kevin is going to be able to have enough money for the concert the fastest

Philip needs at least 4 weeks

Kevin needs at least 3 weeks

Step-by-step explanation:

<u>Philip</u>

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Let's call x to the number of weeks Philip needs to reach $225.

52.5*x + 45 = 225

52.5*x = 225 - 45

x = 180/52.5

x = 3.43

He needs at least 4 weeks

<u>Kevin</u>

  • 3 hours/day * $7.5/hour *3 days/week = $67.5/week
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Let's call y to the number of weeks Kevin needs to reach $225.

67.5*y + 30 = 225

67.5*y = 225 - 30

y = 195/67.5

y = 2.9

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4 years ago
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artcher [175]

Answer:

B and C

Step-by-step explanation:

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4 years ago
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Answer:

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nadya68 [22]

Answer:

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Step-by-step explanation:

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But OD=OB= Radius of the circle.

Therefore

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BDX= 30°

We also know that,

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Therefore,

BAC=BDC(BDX)=30°

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