$(\,2+\,4\,a)\;(\,4+\,3\,b) = $   ?

$\,6 +\,5\,\,b +\,8\,\,a +\,7\,\,a\,b$ $\,12\,\,a\,b +\,8$ $\,8 +\,6\,\,b +\,16\,\,a +\,12\,\,a\,b$ $\,34\,\,a^2\,b^2 +\,8$

$(\,2+\,5\,t)\;(\,5\,t+\,3) = $   ?

$\,25\,\,t^2 +\,6$ $\,10\,\,t^2 +\,15\,\,t +\,5$ $\,50\,\,t +\,6$ $\,25\,\,t^2 +\,25\,\,t +\,6$

$(\,5+\,2\,x)\;(\,y+\,4) = $   ?

$\,5\,\,y +\,20 +\,2\,\,x\,y +\,8\,\,x$ $\,6\,\,y +\,9 +\,3\,\,x\,y +\,6\,\,x$ $\,15\,\,x^2\,y^2 +\,20$ $\,2\,\,x\,y +\,20$

$(\,3+\,b)\;(\,6+\,5\,b) = $   ?

$\,5\,\,b^2 +\,21\,\,b +\,18$ $\,5\,\,b^2 +\,18$ $\,26\,\,b +\,18$ $\,6\,\,b^2 +\,15\,\,b +\,9$

$(\,y\,-5)\;(\,6\,x+\,3) = $   ?

$\,6\,\,x\,y +\,3\,\,y \,-30\,\,x +\,15$ $\,6\,\,x\,y +\,3\,\,y \,-30\,\,x \,-15$ $\,6\,\,x\,y \,-3\,\,y \,-30\,\,x \,-15$ $\,6\,\,x\,y +\,3\,\,y +\,30\,\,x \,-15$

$(\,4+\,5\,x)\;(\,-1\,-\,y) = $   ?

$\,-4 +\,4\,\,y \,-5\,\,x +\,5\,\,x\,y$ $\,-4 \,-4\,\,y +\,5\,\,x \,-5\,\,x\,y$ $\,-4 \,-4\,\,y \,-5\,\,x \,-5\,\,x\,y$ $\,-4 +\,4\,\,y +\,5\,\,x \,-5\,\,x\,y$

$(\,t\,-1)\;(\,t+\,6) = $   ?

$\,\,t^2 \,-7\,\,t \,-6$ $\,\,t^2 +\,5\,\,t +\,6$ $\,\,t^2 \,-5\,\,t \,-6$ $\,\,t^2 +\,5\,\,t \,-6$

$(\,5\,a\,-2)\;(\,-4\,-3\,b) = $   ?

$\,-20\,\,a +\,15\,\,a\,b +\,8 \,-6\,\,b$ $\,-20\,\,a \,-15\,\,a\,b +\,8 +\,6\,\,b$ $\,20\,\,a +\,15\,\,a\,b +\,8 +\,6\,\,b$ $\,-20\,\,a \,-15\,\,a\,b +\,8 \,-6\,\,b$

$(\,a\,-1)\;(\,6\,-4\,a) = $   ?

$\,-4\,\,a^2 +\,10\,\,a \,-6$ $\,4\,\,a^2 +\,10\,\,a \,-6$ $\,4\,\,a^2 \,-2\,\,a \,-6$ $\,4\,\,a^2 +\,10\,\,a +\,6$

$(\,1\,-\,y)\;(\,-\,y\,-1) = $   ?

$\,\,y^2 \,-1$ $\,\,y^2 \,-1$ $\,\,y^2 +\,2\,\,y \,-1$ $\,\,y^2 \,-2\,\,y \,-1$