SOLUTION: I am totatly lost with evaluating please help. problem: 26) 2/3 ab, for a = 7 and b = 4 1/5 27) 4 + mn, for m = 7 2/5 and n = 3 1/4

Algebra ->  Expressions -> SOLUTION: I am totatly lost with evaluating please help. problem: 26) 2/3 ab, for a = 7 and b = 4 1/5 27) 4 + mn, for m = 7 2/5 and n = 3 1/4      Log On


   

Question 149955This question is from textbook
: I am totatly lost with evaluating please help.
problem: 26) 2/3 ab, for a = 7 and b = 4 1/5
27) 4 + mn, for m = 7 2/5 and n = 3 1/4 This question is from textbook

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
# 26

First convert the mixed number b=4%261%2F5 into the improper fraction b=21%2F5 note: let me know if you need help with fraction conversion.


%282%2F3%29+ab Start with the given expression.


%282%2F3%29%287%29%2821%2F5%29 Plug in a=7 and b=21%2F5


%282%2A7%2A21%29%2F%283%2A5%29 Combine the fractions



%282%2A7%2A3%2A7%29%2F%283%2A5%29 Factor 21 into 3%2A7


%282%2A7%2Ahighlight%283%29%2A7%29%2F%28highlight%283%29%2A5%29 Highlight the common terms.



%282%2A7%2Across%283%29%2A7%29%2F%28cross%283%29%2A5%29 Cancel the common terms.


%282%2A7%2A7%29%2F%285%29 Simplify


%2898%29%2F%285%29 Multiply 2, 7, and 7 to get 98



So %282%2F3%29+ab=%2898%29%2F%285%29 when a=7 and b=21%2F5


If you want the approximate answer, then %282%2F3%29+ab=19.6 when a=7 and b=21%2F5







First convert the mixed number m+=+7%262%2F5 into the improper fraction 37%2F5. Also, convert the mixed number n+=+3%261%2F4 into the improper fraction n=13%2F4



4+%2B+mn Start with the given expression.


4+%2B+%2837%2F5%29%2813%2F4%29 Plug in a=37%2F5 and b=13%2F4


4+%2B+%2837%2A13%29%2F%285%2A4%29 Combine the fractions.


4+%2B+%28481%29%2F%285%2A4%29 Multiply 37 and 13 to get 481


4+%2B+%28481%29%2F%2820%29 Multiply 5 and 4 to get 20



4%2820%2F20%29%2B%28481%29%2F%2820%29 Multiply 4 by 20%2F20.


80%2F20%2B481%2F5 Combine and multiply the fractions.



561%2F20 Add the fractions.


So 4+%2B+mn=561%2F20 when a=37%2F5 and b=13%2F4



If you want the approximate answer, then 4+%2B+mn=28.05 when a=37%2F5 and b=13%2F4