WAEC - Mathematics (2008 - No. 28)
Find the quadratic equation whose roots are c and -c
x2 - c2 = 0
x2 + 2cx = 0
x2 + 2cx + c2 = 0
x2 - 2cx + c2 = 0
คำอธิบาย
Roots; x and -c
sum of roots = c + (-c) = 0
product of roots = c x -c = -c2
Equation; x2 - (sum of roots) x = product of roots = 0
x2 - (0)x + (-c2) = 0
x2 - c2 = 0
sum of roots = c + (-c) = 0
product of roots = c x -c = -c2
Equation; x2 - (sum of roots) x = product of roots = 0
x2 - (0)x + (-c2) = 0
x2 - c2 = 0