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sveta [45]
2 years ago
9

Solve the equation 4n2 − 16n − 84 = 0 by completing the square.

Mathematics
1 answer:
melomori [17]2 years ago
8 0

4n² - 16n - 84 = 0

Multiply both sides by 1/4 :

n² - 4n - 21 = 0

Add 21 to both sides:

n² - 4n = 21

Complete the square by adding 4 to both sides:

n² - 4n + 4 = 25

(n - 2)² = 25

Solve for n :

n - 2 = ± √25

n - 2 = ± 5

n = 2 ± 5

Then n = 2 + 5 = 7 or n = 2 - 5 = -3.

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Pls pls pls help me I will mark you brainest
Usimov [2.4K]
The answer is 288 :)
3 0
3 years ago
The longest length of a sail on Jessica's sailboat is 12v40 feet long. Which number is equivalent to this length?
NISA [10]

Answer:48V/10

Step-by-step explanation:

I got it right from Khan Academy

3 0
2 years ago
3n + 14= --4 What is the answer
andre [41]

Answer: n = -6

Step-by-step explanation:

3n+14=-4

Subtract 14 from both sides.

3n+14-14=-4-14

Simplify

3n=-18

Divide both sides by 3

3n/3 = -18/3

n=-6

5 0
3 years ago
Read 2 more answers
100 points!! Brainliest if correct!!
Elena-2011 [213]

surface area (S) of a right rectangular solid is:

S = 2*L*W + 2*L*H + 2*W*H (equation 1)

where:

L = length

W = width

H = height

-----

you have:

L = 7

W = a

H = 4

-----

formula becomes:

S = 2*7*a + 2*7*4 + 2*a*4

simplify:

S = 14*a + 56 + 8*a

combine like terms:

S = 22*a + 56

-----

answer is:

S = 22*a + 56 (equation 2)

-----

to prove, substitute any value for a in equation 2:

let a = 15

S = 22*a + 56 (equation 2)

S = 22*15 + 56

S = 330 + 56

S = 386

-----

since a = 15, then W = 15 because W = a

go back to equation 1 and substitute 15 for W:

S = 2*L*W + 2*L*H + 2*W*H (equation 1)

where:

L = length

W = width

H = height

-----

you have:

L = 7

W = 15

H = 4

-----

equation 1 becomes:

S = 2*7*15 + 2*7*4 + 2*15*4

perform indicated operations:

S = 210 + 56 + 120

S = 386

-----

surface area is the same using both equations so:

equations are good.

formula for surface area of right rectangle in terms of a is:

S = 22*a + 56

-----

8 0
3 years ago
Read 2 more answers
I don't know what ten times 10 is?
Scrat [10]
I hope this helps you

?=10×10

?=100
6 0
3 years ago
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