27.3  Rekenregels voor wortels 1 >
1
a

-

b

Ja, nee

c

( 7 9 ) 2 = 7 9 7 9 = 7 7 9 9 = 7 9 = 63

d

55

2
a

5 2 + 3 2 = 8 , dus de schuine zijde is 8 .

b

De twee rechthoekszijden samen zijn langer dan de schuine zijde (de kortste verbinding van twee punten is een rechte lijn).

3
a

20

50

75

b

5 a 2

4 a

a 2 b

4
5
a

8 = 4 2 = 2 2

28 = 4 7 = 2 7

18 = 9 2 = 3 2

48 = 16 3 = 4 3

b

20 = 4 5 = 2 5

60 = 4 15 = 2 15

40 = 4 10 = 2 10

80 = 16 5 = 4 5

c

7 25 = 1 25 7 = 1 5 7

7 100 = 1 100 7 = 1 10 7

7 36 = 1 36 7 = 1 6 7

3 49 = 1 49 3 = 1 7 3

4s
5s

Bovenste rij:
72 = 36 2 = 6 2
76 = 4 19 = 2 19
80 = 16 5 = 4 5
84 = 4 21 = 2 21

Onderste rij:
12 49 = 1 7 12 = 1 7 4 3 = 2 7 3
48 49 = 1 7 48 = 1 7 16 3 = 4 7 3
2 2 25 = 52 25 = 1 5 52 = 1 5 4 13 = 2 5 13
10 b 2 = 1 b 10

6
a

0

b

160 = 16 10 = 4 10 , 90 = 9 10 = 3 10 , dus 160 90 10 = 4 10 3 10 10 = 0

7
9
a

9 3 + 25 3 = 3 3 + 5 3 = 8 3
4 2 + 9 2 = 2 2 + 3 2 = 5 2
10 + 100 10 = 10 + 10 10 = 11 10

b

9 5 4 5 = 3 5 2 5 = 5
16 2 4 2 = 4 2 2 2 = 2 2
100 3 3 = 10 3 3 = 9 3

c

a + 4 a = a + 2 a = 3 a
4 3 + 1 4 3 = 2 3 + 1 2 3 = 2 1 2 3
1 4 3 + 1 16 3 = 1 2 3 + 1 4 3 = 3 4 3

8
a

6

b

12 3 = 36 = 6

c

6 2 = 12 = 4 3 = 2 3

7s
9s
a

2 9 + 8 9 = 1 3 2 + 2 3 2 = 2 ;
1 1 4 + 11 1 4 = 5 4 + 45 4 = 1 2 5 + 1 1 2 5 = 2 5

b

2 2 + 4 2 + 8 2 + 16 2 = 30 2 , dus het getal 30 .

10
12

1 = 1

16 = 4

4 = 2

81 = 9

10

64 = 8

11

2 + 1 4 > 2 1 4

9 + 16 > 25

4 2

1 + 100 > 101

10s
12s
a

3 + 4 = 7 = x , dus x = 7 2 = 49

b

10 + 0,1 = 10,1 = x , dus x = 10,1 2 = 102,01

c

2 x = 2 , x = 1 2 2 , dus ( 1 2 2 ) 2 = 1 4 2 = 1 2

d

x 0,02 = 2 , dus x = 2 0,02 = 100 = 10

e

x = 10 3 2 3 = 8 3 , dus x = ( 8 3 ) 2 = 64 3 = 192

f

1 = ( x + 1 ) ( x 1 ) = x 1 , dus x = 2