If a, b and c are different integers such that a < b < c < 0, then which of the following statements is true?
a + c < b
ab < c
a + b > c
ac > ab
In standard form, the number 829030000 is expressed as k x 10n. The value of k + n is
90.903
16.2903
15.2903
91.903
If x is an integer, then (x+1)4-(x-1)4 is always divisible by
6
8
9
12
B.
8
Consider (x+1)4-(x-1)4
[(x+1)2]2 - [(x-1)2]2
[x2+1+2x]2- [x2+1-2x]2
(x2+1+2x+x2+1-2x) (x2+1+2x-x2-1+2x)
(2x2+2)(4x)
2(x2+1)(4x)
8x(x2+1)
Hence if x is an integer , then (x+1)4-(x-1)4 will be always divisible by 8 .
A has 20% more money than B and C has 20% less money than B. What percent more money does A have than C?
30
50
17
43