Solve For x

[nycmathguy]

Set 1.3
Question 75 (a-b)

See attachment.

I see no need to solve for x. Value of x given. I must replace x in the given problem and simplify.

 

[MathLover1]

you just need to show that 1/x=1/a+1/b is same as x=ab/(a+b)

 

[nycmathguy]

you just need to show that 1/x=1/a+1/b is same as x=ab/(a+b)

Ok. I am going to be very busy between July 16 and August 6. In addition to my regular overnight hours, the boss requested for me to cover weekend hours for a vacationing coworker. Don't cheer. I am upset. I like my days off to do math and enjoy the beach, movies, etc. Just wanted to let you know.

 

[MathLover1]

ok,

 

[nycmathguy]

ok,

I may continue to post questions but to show my work will take a few days. I am on this NO REST schedule for 3 weeks. I should have said no when the manager requested coverage.

 

[MathLover1]

75.
given:
1/x=1/a+1/b

a)

solve to show x =ab/(a+b), provided

1/x=1/a+1/b

1/x=b/ab+a/ab

1/x=(a+b)/ab...........cross multiply

ab=x(a+b)

x=ab/(a+b)

b) check the solution

1/x=1/a+1/b..............substitute x

1/(ab/(a+b))=1/a+1/b

(a+b)/ab=1/a+1/b

a/ab+b/ab=1/a+1/b

1/b+1/a=1/a+1/b-> true

 

[nycmathguy]

75.
given:
1/x=1/a+1/b

a)

solve to show x =ab/(a+b), provided

1/x=1/a+1/b

1/x=b/ab+a/ab

1/x=(a+b)/ab...........cross multiply

ab=x(a+b)

x=ab/(a+b)

b) check the solution

1/x=1/a+1/b..............substitute x

1/(ab/(a+b))=1/a+1/b

(a+b)/ab=1/a+1/b

a/ab+b/ab=1/a+1/b

1/b+1/a=1/a+1/b-> true

I was going to work it out when time allows. I'm just going to be extra busy for a few weekends working my regular 40-hour shift plus 26 OT hours. By the way, I dislike OT. I agreed to work for a vacationing coworker to keep the boss happy. The algebra for this problem is doable.