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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.

 Mar 20, 2020
 #1
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This is a very simple way to solve it:

 

We know that the x^2 terms come from:  (-4)*(-7)+2t+(-5)*1

                                                                 28 + 2t -5

                                                                 23 + 2t

 

If we want this equal to zero, we must have 23+2t = 0 

                                                                      t = -11.5

 

Hope this helped!

 Mar 20, 2020
edited by CalTheGreat  Mar 20, 2020
 #2
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Thank you!

Guest Mar 20, 2020

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