True or false. if a is any odd integer, then a^2 + a is even. explain this.

True.

Step-by-step explanation:

We can represent an odd number by 2n + 1 where n = 0, 1, 2, 3, 5 etc.

Substituting:

a^2 + a = (2n + 1)^2 + 2n + 1

=  4n^2 + 4n + 1 + 2n + 1

= 4n^2 + 6n + 2

= 2(2n^2 + 3n + 1)

which is even because any integer multiplied by an even number is even.

This is also true if we use a negative odd integer:

We have 4n^2 + 4n + 1  - 1 - 2n

= 4n^2 + 2n

=  2(2n^2 + n(.

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)