Question 355708
Doesn't matter which you do first, you should get the same answer.
Use the FOIL method for both.
{{{(2t+3)(2t+3)=4t^2+6t+6t+9}}}
{{{(2t+3)^2=4t^2+12t+9}}}
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{{{(t-1)(t+1)=t^2+t-t-1}}}
{{{(t-1)(t+1)=t^2-1}}}
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{{{(2t+3)^2 - (t-1)(t+1)=(4t^2+12t+9)-(t^2-1)}}}
{{{(2t+3)^2 - (t-1)(t+1)=4t^2+12t+9-t^2+1}}}
{{{(2t+3)^2 - (t-1)(t+1)=highlight(3t^2+12t+10)}}}