Find t if the expansion of the product of x^3 - 4x^2 + 2x - 5 and x^2 + tx - 7 has no x^2 term.

x² terms come from:  (-4)*(-7) + 2t + (-5)*1 → 28 + 2t -5 → 23 + 2t

 

For this to be zero we must have 23 + 2t = 0. or t = -23/2 → -11.5

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