If a + b = 5 and a - b = √17 then the value of ab should be _____?
If a + b = 5 and a - b = √17 then the value of ab should be _____?
Explanation
Given:
a + b = 5
a - b = √17
Square both equations:
(a + b)² = 5²
a² + 2ab + b² = 25
(a - b)² = (√17)²
a² - 2ab + b² = 17
Subtract the second equation from the first:
4ab = 8
Divide by 4:
ab = 2