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kow [346]
3 years ago
10

Solve x 2 - 4x - 7 = 0 by completing the square. What are the solutions?

Mathematics
1 answer:
Bingel [31]3 years ago
3 0

Answer:

x = 2±sqrt(11)

Step-by-step explanation:

x^2 -4x - 7 =0

Add 7 to each side

x^2 -4x -7+7 =0+7

x^2 -4x =7

To complete the square take the coefficient of the x term and  divide by 2 and then square it.  Add it to both sides

-4 /2 = -2 then square

(-2)^2 = 4

Add 4 to both sides

x^2 -4x+4 =7+4

x^2 -4x+4 = 11

Factor the left side into (x-b/2)^2

(x-2)^2 =11

Take the square root of each side

sqrt((x-2)^2) =±sqrt(11)

x-2 = ±sqrt(11)

Add to to each side

x-2+2 = 2±sqrt(11)

x = 2±sqrt(11)

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Ostrovityanka [42]

Hello from MrBillDoesMath!

Answer:

See Discussion below

Discussion:

A function f is even if f(-x) = f(x)


f(x)                               f(-x)                                  Are they equal?

----------------------------------------------------------------------------------------

-x^8 + 2x^6-5x           -(-x)^8 + 2(-x)^6 + 5x         No

3 abs(x) - 4                 3 abs(-x) -4                       Yes

log5 x^2                     log5 (-x)^2                        Yes

(6x)^ (1/7)                     (-6x)^(1/7)                          No

e^(x^2-x)                     e^( (-x)^2+x)                      No

(x^8 +5x^2)^(-1)           ( (-x)^8 + 5 (-x)^2) ^(-1)      Yes


Answers with Yes, above are even functions.

Regards,  

MrB

P.S.  I'll be on vacation from Friday, Dec 22 to Jan 2, 2019. Have a Great New Year!


6 0
3 years ago
Help please thank you if u do!
dmitriy555 [2]
I think d but i might be wrong :( sorry
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3 years ago
Read 2 more answers
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