Question

1) stiind că a-b=4 si a²-b²=24 , calculati a+b
2) a+b=4 si a·b= 2 , calculati 1/a+1/b
3) a+b=4 si a·b=2 , calculati a²+b²

cu rezolvare vă rog , dau coroana

Answer 1

1)
a^2 - b^2 = (a+b)(a-b)=4(a+b)=24
a+b = 24/4=6

2)
1/a + 1/b = (a+b)/ab = 2*4=8

3)
(a+b)^2 = 16 = a^2 +b^2 +2ab = a^2 + b^2 +4
a^2 +b^2 = 16 -4 = 12

Answer 2

Vom folosi formula: a² - b²=(a-b)(a+b)
a)a²-b²=24
  (a-b)(a+b)=24
    4(a+b)=24
      a+b=6
b)1/a+1/b=  a+b/ab= 4/2 =2

c) a·b=2⇒2·a·b=4
a+b=4 |()²
(a+b)²=16
a²+2·a·b+b²=16
a²+b²+4=16
a²+b²=12