A) This is a repeating decimal which means it is possible to write it in the form p/q where p & q are integers and q is nonzero. So we can rule out choice A.
B) Similar to the answer choice above, we have another repeating decimal. So we can rule out choice B.
C) This is a terminating decimal. It does not go on forever. We can write this as a fraction (0.7 = 7/10). So we can rule out choice C.
D) This is also terminating so it seems like your teacher made a typo. What I'm thinking is that the 3.14 was meant to be a decimal that goes on forever without a pattern. This is a well known number called pi. I'm assuming that's what your teacher was going for.
So I'd go with choice D as the answer.
Scientific notation is
x*10^y such that
1<u><</u>x<10
780=7.8 times 100=7.8 times 10^2
7.8*10^2
The volume of the cube would be S^3, where S is the length of the side.
Volume = (5a + 4b)^3
Which becomes:
(5a+4b)(5a+4b)(5a+4b)
Multiply the first two sets of parenthesis by each other:
(25a^2+40ab+16b^2)(5a+4b)
Now multiply that by the 3rd set of parenthesis to get:
125a^3+300a^2b + 240ab^2 + b^3
