Let f(x) =
. We can see that f(x) is a quadratic function.
For, f(x) > 0, Discriminant (D) < 0
Therefore, integer values that 'a' can take = {-3, -2, -1, 0, 1, 2, 3}
Let g(x) =
. We can see that g(x) is also a quadratic function.
For, g(x)≥0, Discriminant (D) ≤ 0
Therefore, integer values that 'b' can take = {-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5}
We have to find out the largest possible value of 2a -6b .The largest possible value will occur when 'a' is maximum and 'b' is minimum.
Therefore, the largest possible value of = 2*3 - 6*(-5) = 36.