Answer:
a) SAS
b) Volume of DEF is 4 times the Volume of ABC
Step-by-step explanation:
a) since they have one same/congruent angle (angle B and angle E) and other two sides are in the same ratio, they are similar by SAS similarity theorem.
40/20 = 30/15 = 2
Therefore Δ ABC is similar to Δ DEF
b) Volume of a prism
= base area × height
Let height be 'h cm'
With Base ABC:
Volume = ½×20×15×h = 150h cm³
With Base DEF:
Volume = ½×40×30×h = 600h cm³
600h/150h = 4
Prism with base DEF has a greater volume; it's 4 times of the volume of the prism with base ABC
To perform this check, you must use the following theorem: 
is a lower bound for the zeroes of 
if, when divide by 
, the quotient and the remainter alternate signs.
Since the long division yields the result
You can see that the signs don't alternate (the last two terms are positive). So, -1 is not a lower bound.
In fact, the actual roots of the polynomial are -3, -2, 1, 3, so as you can see there are roots smaller than -1.
