Question

If alpha and beta are the zeros of polynomial 3x^2 -2x -21 evaluate 1/alpha+1/beta

Answer 1

get the zeroes by splitting middle term

alpha = -9

beta =7

1/alpha +1/beta = (alpha + beta)/alpha×beta

= either put -b/a or c/a for (alpha + beta) and (alpha ×beta) respectively or use the got values

ans = 2/63

Answer 2

the final answer according to me should be -2/21