Find t if the expansion of the product of 2x3+x2−3x+5 and 7x2+tx−4 has no x2 term.
The x^2 term will come from
-4 * x^2 - (3t) x^2 + (5*7)x^2 =
(-4 - 3t + 35) x^2 =
(31 - 3t) x^2
If this has no x^2 term , then 31 - 3t = 0 → 31 = 3t → t = 31 / 3
