if a and b are the roots of the equation x 2 - 9 x + 20 = 0 , find the value of a 2 + b 2 + ab ?
"a 2 + b 2 + ab = a 2 + b 2 + 2 ab - ab i . e . , ( a + b ) 2 - ab from x 2 - 9 x + 20 = 0 , we have a + b = 9 and ab = 20 . hence the value of required expression ( 9 ) 2 - 20 = 61 . option c"
add(power(divide(subtract(9, sqrt(subtract(power(9, 2), multiply(const_4, 9)))), 2), 2), power(divide(add(9, sqrt(subtract(power(9, 2), multiply(const_4, 9)))), 2), 2))