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3 years ago

when asked to factor the trinomial x^2-18x+81 a student gives the answer (x-9(x+9) which of the following statements is true

Mathematics

2 answers:

Alex17521 [72]3 years ago

5 0

the answer is incorrect; the plus sign should be a minus sign

charle [14.2K]3 years ago

3 0

(x - 9)(x + 9) would give you x^2 - 81 when you get a plus and minus like that after you factor the middle term is canceled out so the answer would be (x - 9)^2

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Challenge fr y'all. solve this to get 50 points and brainliest coming up if you get the right answer

TEA [102]

Answer:

See below

Step-by-step explanation:

Use the law of cosines:

$AB=\sqrt{PA^2+PB^2-2*PA*PB*cosP}$
$AB=\sqrt{60^2+100^2-2*60*100*cos80} =\sqrt{11516.22} =107.31$

ii)

Use the law of sines:

sin ∠A / PB = sin ∠P / AB
sin ∠A / 100 = sin 80 / 107.31
sin ∠A = 100 sin 80 deg / 107.31
sin ∠A = 0.92
∠A = arcsin 0.92
∠A = 67° (rounded)

iii)

Bearing of B from A:

90° + (67° - 30°) =
127°

PB is longer distance. Time to reach B:

t = d/s
t = 100/20 = 5 hours

The speed s of the slower ship:

s = d/t
s = 60/5 = 12 km/h

3 0

2 years ago

Read 2 more answers

Suppose a population of rodents satisfies the differential equation dP 2 kP dt = . Initially there are P (0 2 ) = rodents, and t

WINSTONCH [101]

Answer:

Suppose a population of rodents satisfies the differential equation dP 2 kP dt = . Initially there are P (0 2 ) = rodents, and their number is increasing at the rate of 1 dP dt = rodent per month when there are P = 10 rodents.

How long will it take for this population to grow to a hundred rodents? To a thousand rodents?

Step-by-step explanation:

Use the initial condition when dp/dt = 1, p = 10 to get k;

$\frac{dp}{dt} =kp^2\\\\1=k(10)^2\\\\k=\frac{1}{100}$

Seperate the differential equation and solve for the constant C.

$\frac{dp}{p^2}=kdt\\\\-\frac{1}{p}=kt+C\\\\\frac{1}{p}=-kt+C\\\\p=-\frac{1}{kt+C} \\\\2=-\frac{1}{0+C}\\\\-\frac{1}{2}=C\\\\p(t)=-\frac{1}{\frac{t}{100}-\frac{1}{2} }\\\\p(t)=-\frac{1}{\frac{2t-100}{200} }\\\\-\frac{200}{2t-100}$

You have 100 rodents when:

$100=-\frac{200}{2t-100} \\\\2t-100=-\frac{200}{100} \\\\2t=98\\\\t=49\ months$

You have 1000 rodents when:

$1000=-\frac{200}{2t-100} \\\\2t-100=-\frac{200}{1000} \\\\2t=99.8\\\\t=49.9\ months$

7 0

3 years ago

The area of a particular rectangle is 72. If the length of the rectangle is twice

soldier1979 [14.2K]

Answer:

Step-by-step explanation:

Suppose the width is "a". Then the length is 2a.

2(a²) =72 Divide both sides by 2

a²= 36

a=6

4 0

3 years ago

Greg is designing a clock face. Using the center of the clock face as the origin, he keeps its diameter at 10 units. Match the p

Alex17521 [72]

3o'clock - directly to the right of the origin; on the x axis - (5,0)
6o'clock - directly below the origin; on the y-axis - (0,-5)
9o'clock - directly to the left of the origin; on the x-axis, (-5,0)
12o'clock - directly above the origin; on the y-axis, - (5,0)

7 0

3 years ago

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A cyclist rides his bike at a rate of 21 miles per hour. What is this rate in miles per minute? How many miles will the cyclist

Citrus2011 [14]

5 days ago, hope this still helps though!

Alright 21 miles per hour. We know that there are 60 minutes in an hour. So this is basically saying 21 miles per 60 minutes. To find the rate for miles per minute, you divide 21 by 60 which is 0.35.

In one minute the cyclist rides 0.35 miles
In two minutes the cyclist rides 0.7 miles

5 0

2 years ago