Step-by-step explanation:
Answer:
The second choice is the correct one.
Step-by-step explanation:
20x^4 - 45x^2
GCF is 5x^2, so the factors are:
5x^2( 4x^2 - 9)
Now 4x^2 - 9 is the differencr of 2 squares:
4x^2 - 9 = (2x + 3)(2x - 3)>
The 4th factor would be 3. You would find this out through a factor tree. If you don't know the original number when you start you look at your numbers. A factor of 1 usually goes with the highest number, assuming that the number 6 is the highest factor, that would be the original number. As 2 is the other known factor than we know that 3 has to be the last factor, because 2 x 3 = 6. It cannot be the number 12 because then there would be 6 factors not the needed 4.
Answer:
63
Step-by-step explanation:
12x6=72
72-9=63
the answer is 63
