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Andreas93 [3]
2 years ago
9

Solve x4 - 11x2 + 18 = 0.

Mathematics
2 answers:
VashaNatasha [74]2 years ago
8 0

Answer:

The second answer is correct.

Step-by-step explanation:

Mark brainliest if correct please

lara31 [8.8K]2 years ago
6 0

Answer:

x=√2, x=-√2, x= 3 and x=-3

Step-by-step explanation:

We need to solve the equation x^4 - 11x^2+18=0  

We can replace x^4 = u^2 and x^2 = u

So, the equation will become

u^2 -11u+18 = 0

Factorizing the above equation:

u^2 -9u-2u+18 =0

u(u-9)-2(u-9)=0

(u-2)(u-9)=0

u=2, u=9

As, u = x^2, Putting back the value:

x^2 =2 , x^2 =9  

taking square roots:

√x^2 =√2 ,√x^2=√9  

x=±√2 , x = ±3

so, x=√2, x=-√2, x= 3 and x=-3

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liraira [26]

Answer:

-6

Step-by-step explanation:

14x+6=2(5+7x)

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3 0
3 years ago
Work out the formula of the nth term in the following quadratic sequence:<br> 19, 15, 9, 1...
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In a quadratic sequence we'll get a linear first difference and a constant second difference.  Let's verify that.

n          1   2   3   4

f(n)       19  15  9   1

1st diff   -4  -6  -8

2nd diff     2   2

We see that we got a constant second difference.  We could just extend that and work back up to get more values.

n          1   2   3   4       5    6      7

f(n)       19  15  9   1      -9   -21   -35

1st diff   -4  -6  -8   -10  -12   -14

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That's just an aside; we're after the general formula.  We have

f(1)=19, f(2)=15, f(3)=9

In general we can assume

f(n) = an²  + bn + c

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15 = a(2²) + b(2) + c = 4a + 2b + c

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4 = -3a - b

6 = -5a - b

Subtracting those,

-2 = 2a

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b = -3a -4 = -1

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Check:

f(1) = -1 - 1 + 21 = 19, good

f(2) = -4 - 2 + 21 = 15, good

f(3) = -9 - 3 + 21 = 9, good

f(4) = -16 - 4 + 21 = 1, good

Let's check our extended table, how about

f(7)= -49 - 7 + 21 = -35, good

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Igoryamba
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