Find t if the expansion of the product of x^3 - 4x^2 + 5x - 5 and x^2 + tx - 7 has no x^2 term.
+592 (x3 - 4x2 + 5x - 5)(x2 + tx - 7)
Find the pairs that make x2 terms:
(-4x2)(-7) + (5x)(tx) + (-5)(x2)
= 28x2 + 5tx2 - 5x2
= 23x2 + 5tx2
Since you're trying to find no x2 term:
23x2 + 5tx2 = 0
23 + 5t = 0
5t = -23
t = \(-\frac{23}{5} \) or -4.6
