Given #f(n)=n-4# and #g(n)=2n#, how do you find #3f(n)+5g(n)#?

1 Answer
SagarStudy
Oct 26, 2016

#3f(n)+5g(n)=13n-12#

Explanation:

#f(n)=n-4.............(i)#
#g(n)=2n..................(ii)#

To find out: #3f(n)+5g(n)#

Multiply #(i)# by #3#.
#3f(n)=3(n-4)#
#implies 3f(n)=3n-12...................(iii)#

Multiply #(ii)# by #5#.
#5g(n)=5(2n)#
#implies 5g(n)=10n......................(iv)#

Now, Add #(iii)# and #(iv)#

#implies 3f(n)+5g(n)=3n-12+10n#
#implies 3f(n)+5g(n)=13n-12#

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