If a - b = 8 and ab = 9, then the value of a + b is
Answer & explanation
Correct answer: option 4
a - b = 8
ab = 9
( a - b )2 = a2 + b2 - 2ab
( 8 )2 = a2 + b2 - 2 × 9
64 = a2 + b2 - 2 × 9
a2 + b2 = 82
a + b = \(\sqrt {82 + 2 × 9}\)
a + b = ±10
If a - b = 8 and ab = 9, then the value of a + b is
Correct answer: option 4
a - b = 8
ab = 9
( a - b )2 = a2 + b2 - 2ab
( 8 )2 = a2 + b2 - 2 × 9
64 = a2 + b2 - 2 × 9
a2 + b2 = 82
a + b = \(\sqrt {82 + 2 × 9}\)
a + b = ±10