Question

If (a + 2b) = 6 and ab = 4, then
(2/a+1/b)
find out answer​

Answer 1

Answer: 3/2

Step-by-step explanation:

a+2b = 6

a = 6-2b --------------(1)

ab = 4 (substitute (1) here)

(6-2b)(b) = 4

6b - 2b² = 4

2b² - 6b +4 = 0 (divide by 2 throughout the eqn.  on both sides)

b² - 3b +2 = 0

b² - 2b - b +2 = 0

b ( b -2 ) -1 ( b - 2 ) = 0

=> (b-1)(b-2) = 0

=> b = 1,2

=> a = 4,2

2/a +1/b = 2/4 +1/1 = 1/2 +1 = 3/2

2/a + 1/b = 2/2 +1/2 = 1 +1/2 = 3/2

Therefore 2/a +1/b = 3/2 in both the cases

Answer 2

3/2 is the right answer..