Question

stie cineva sa rezolve oricare din problemele de la 13 la 20?va rog

Answer 1

Răspuns:

Explicație pas cu pas:

13)a=26  ipotenuza, b, c catetele

b/1/5=c/1/12=k

b=k/5

c=k/12

din t lui Pitagora a²=b²+c²

676=k²/25+k²/144

676x3600=144k²+25k²

676x3600=169k²

k²=4x3600, k=2x60=120

b=120/5=24

c=120/12=10

P=a+b+c=26+24+10=60 cm

14)x=lungime drum

2x/5=ziua 1

2x/5 × 2/3=4x/15=ziua 2

2x/5+4x/15+40=x

6x+4x+600=15x

5x=600x=120 km

2x/5=2×120/5=48 km ziua 1

4x/15=4×120/15= 32 km ziua 2

40 km ziua 3

15)Ai in imagine

16)(a+b+c):3=53

a+b+c=159

c=3a

a:b=2rest6

a=2b+6

b ,--,

a ,--,--,+6 ,

c ,--,--,--,--,--,--,+18 , } 159

159-24=135

b=135:9

b=15

a=15•2+6

a=36

c=36•3

c=108

17)a/b

b=numitor

a=numarator

b=2a+3

b-9=a+2

(2a+3)-9=a+2

2a+3=a+2+9

2a+3=a+11

2a=a+(11-3)

2a=a+8

=> a=8

b=2*8+3=19

18)Ai in imagine

19)Notezi cu x numarul cautat. Conform enuntului problemei, formezi urmatoarea ecuatie

((2*x-7)*6-2)/5=20 pe care o rezolvi ca sa aflii numarul

(2*x-7)*6-2=5*20 => 12*x-44=100 => 12*x=144  

=> x =12

20)a^2-b^2=176

(a-b)(a+b)=176

a+b=44

(a-b)•44=176

a-b=176:44

a-b=4. a=b+4

a+b=44. b+4+b=44 2b=44-4. 2b=40 b=20

a=b+4. a=20+4. a=24

proba a+b=44; 24+20=44