given 3<a<4,4<b<5
find 1/a+1/b
?<1/a+1/b<?
4 answers
Please help fast
impatient much?
1/a is smallest when a is largest, so
1/4 + 1/5 < 1/a + 1/b < 1/3 + 1/4
1/a is smallest when a is largest, so
1/4 + 1/5 < 1/a + 1/b < 1/3 + 1/4
If 3<a<4
then 1/3 > 1/a > 1/4, or
1/4 < 1/a < 1/3 , #1
if 4<b<5
then 1/4 > 1/b > 1/5 , or
1/5 < 1/b < 1/4 , #2
add #1 and #2
1/4+1/5 < 1/a + 1/b < 1/3+1/4
9/20 < (1/a + 1/b) < 7/12
then 1/3 > 1/a > 1/4, or
1/4 < 1/a < 1/3 , #1
if 4<b<5
then 1/4 > 1/b > 1/5 , or
1/5 < 1/b < 1/4 , #2
add #1 and #2
1/4+1/5 < 1/a + 1/b < 1/3+1/4
9/20 < (1/a + 1/b) < 7/12
@oobleck why so rude lol, he just want people to do it fast cause he is anxious probably