Question

media aritmetica a doua nr rationale este 150. sa se afle nr stiind ca sunt invers proportionale cu nr 4 si 5.

Answer 1

a+b=150.2=300
a.4=b.5=k
a=k/4
b=k/5
k/4+k/5=300
5k+4k=20.300
9k=6000
k=6000/9=2000/3
a=2000/3:1/4=500/3
b=2000/3:1/5=400/3

Answer 2

ma=(a+b)/2=150

a+b=150*2

a+b=300

a,b  ip  cu 4,5

4a=5b=k

a=k/4
b=k/5

k/4+k/5=300  aducem la acelasi numitor

5k+4k=6000

9k=6000

k=6000/9= 2000/3

a=2000/3/4=  2000/3 * 1/4= 500/3

b=2000/3/5= 2000/3 *1/5= 400/3