Step-by-step explanation:
The required sum
=(1+2+3+...+199)−(3+6+9+...+198)−(5+10+15+...+195)+(15+30+45+...+195)
=2199(1+199)−266(3+198)−239(5+195)+213(15+195)
=199×100−33×201−39×100+13×105=10732
First make 20 into a fraction, then solve; 3/5 · 20/1. 60/5 = 12. Hope that helps!
320 feet / 40 minutes. This will give an average of 8 feet per minute.
Answer:
Prove set equality by showing that for any element
,
if and only if
.
Example:
.
.
.
.
.
Step-by-step explanation:
Proof for
for any element
:
Assume that
. Thus,
and
.
Since
, either
or
(or both.)
- If
, then combined with
,
. - Similarly, if
, then combined with
,
.
Thus, either
or
(or both.)
Therefore,
as required.
Proof for
:
Assume that
. Thus, either
or
(or both.)
- If
, then
and
. Notice that
since the contrapositive of that statement,
, is true. Therefore,
and thus
. - Otherwise, if
, then
and
. Similarly,
implies
. Therefore,
.
Either way,
.
Therefore,
implies
, as required.
Answer:
Step-by-step explanation:
where is the work