GIAO AN DAY TOAN BANG TIENG ANH LOP 8

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GIAO AN DAY TOAN BANG TIENG ANH LOP 8

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Vinh Tuong Education Departure Vinh Tuong Secondary School... Thank you so much for attending our class.[r]

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1 2 3

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PRACTICE PROBLEMS ON POLYNOMIALS

We have:

n3 - 8n2 + 20n - 13 = (n - 1)(n2 - 7n +13)

Because n3 - 8n2 + 20n - 13 are prime numbers

2

1

7 13 is n

SO

n n a prime          is or

7 13

n a prime n n         

Problem 1: How many positive integers n are A= prime numbersn3  8n2  20n 13

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2

1 1 If

7 13 is 2

n

n n a prime n

           1 is

If 3 or 4

7 13 1

n a prime

n n n n            

PRACTICE PROBLEMS ON POLYNOMIALS

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Problem 2: Solve the following exercises:

If a, b, c are real numbers so that a2 + 4b = 7;

b2 +8c = -10 and c2+ 6a = -26 Find T = a2+ b3+ c4

Solution

2

2 2

2

4

8 10 a + 4b+b +8c+c +6a = 7+(-10)+(-26)

6 26

a b

We have b c

c a            

 a2+ 4b + b2+ 8c + c2+ 6a + 29 =

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 (a + 3)2+ (b + 2)2+ (c + 4)2=

 

2

2

9

3 0 3

2 0 2 8

4 0 4 256

a b c 256 257 a

a a

b b b

c c c

                                     

( a2+ 6a + 9) + ( b2+ 4b + 4) + (c2 + 8c + 16) =

PRACTICE PROBLEMS ON POLYNOMIALS

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PRACTICE PROBLEMS ON POLYNOMIALS

Problem 3: Find the balance polynomial divided by polynomial P(x) =5 + x + x3 + x9 + x27 + x81 for

polynomial Q(x) = x2 -

Solution

We have:

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PRACTICE PROBLEMS ON POLYNOMIALS

= x(x2 - 1) + x(x8 - 1) + x(x26- 1)+x(x80 - 1) + 5x +

Note that a2n – b2n(a - b) from nN.So (x2n-1)(x2 - 1)

 P(x) : Q(x) balance polynomial 5x +

Therefore balance polynomial divided by

polynomial P(x) for polynomial Q(x) is 5x +5

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PRACTICE PROBLEMS ON POLYNOMIALS

Let balance polynomial divided by polynomial P(x) for polynomial Q(x) is R(x) = ax + b (a; b  R)

We have: P(x) = (x2 - 1) A(x) + ax + b

(A(x) is quotient polynomial)

    or 10 10

Apply the Bezout the em We have

P a b

a b

P a b

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PRACTICE PROBLEMS ON POLYNOMIALS

Similar exercises:

Find the balance polynomial divided by polynomial P(x) = x81 + x49 + x25 + x9 +x +

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PRACTICE PROBLEMS ON POLYNOMIALS

V) Homework:

- Review all the exercises that we today - Solve the following exercises:

Question 1: Find the numbers of different positive integer triples (x; y; z) that satisfy equations

x2 + y - z = 100 and x + y2 - z = 124

Question 2: Find the natural numbers x; y; z that satisfy the following conditions:

x3 + y3 = 2z3 x + y + z is a prime number

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