WP-MA: Klasse 9 – Umformen von Summen in Produkte

erarbeitet von R. Bothe

 

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Lösungswege:

Forme die folgenden Summen in Produkte um

a)

14x3 + 7x2 + 21 x

=

7x × (2x2 + x + 3)

 

b)

9y2  + 3y2x - 6yx2

=

3y × (3y + xy - 2x2)

 

c)

3 × (a + b) + a2 × (a + b)

=

(a + b) × (3 + a2)

 

d)

(3x - 2)2 - 3ax + 2a

=

(3x - 2)2 - a (3x - 2)

 

 

 

=

(3x - 2) × (3x - 2 - a)

 

e)

9x3 + 6x2 + 21x +14

=

3x2 × (3x + 2) + 7 × (3x + 2)

 

 

 

=

(3x + 2) × (3x2 + 7)

 

f)

9m2 - 12m + 4

=

(3m - 2)2

 

g)

e2 + 8ex + 16x2

=

(e + 4x)2

 

h)

k2 - 9

=

(k + 3)(k - 3)

 

i)

k4  - 16

=

(k2 + 4)(k2 - 4)

 

 

 

=

(k2 + 4)(k + 2)(k - 2)

 

j)

9x2 - 4y2

=

(3x + 2y)(3x - 2y)

 

k)

2x2 - 20x +50

=

2(x2 - 10x + 25)

 

 

 

=

2(x - 5)2

 

l)

b2 × (a + b ) -  a2 × (a + b)

=

(a + b)(b2 - a2)

 

 

 

=

(a + b)(b + a)(b - a)

 

 

 

=

(a + b)2 × (b - a)

 

 

 

=

- (a + b)2 × (a - b)

 

m)

(x + 3 )2 + 4x3  + 12x2

=

(x + 3)2 +4x2(x + 3)

 

 

 

=

(x + 3)(x + 3 + 4x2)

 

 

 

=

(x + 3)(4x2 + x + 3)

 

n)

x2 × (x - 3) - 4x +12

=

x2 (x - 3) - 4(x - 3)

 

 

 

=

(x - 3)(x2 - 4)

 

 

 

=

(x - 3)(x + 2)(x - 2)

 

o)

x4 - 4x3 - 2x2 + 8x

=

x3(x - 4) - 2x(x - 4)

 

 

 

=

(x - 4)(x3 - 2x)

 

 

 

=

(x - 4) × x × (x2 - 2)

 

 

 

=

x(x - 4)(x + Ö2)(x - Ö2)

 

p)

x2 - 6x - 16

=

(x2 - 6x + 9) - 9 - 16

 

 

 

=

(x - 3)2 - 25

 

 

 

=

(x - 3 + 5)(x - 3 - 5)

 

 

 

=

(x + 2)(x - 8)

 

q)

x3 + 4x2 - 5x

=

x × (x2 + 4x - 5)

 

 

 

=

x × [(x2 + 4x + 4) - 4 - 5]

 

 

 

=

x × [(x + 2)2 - 9]

 

 

 

=

x × (x + 2 + 3)(x + 2 - 3)

 

 

 

=

x × (x + 5)(x - 1)

 

r)

x4 + 5x2 +  6

=

x4 + 3x2 + 2x2 +  6

 

 

 

=

x2 × (x2 + 3) + 2 × (x2 +  3)

 

 

 

=

(x2 + 3)(x2 + 2)

 

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