If #m^2+n^2=12# and #mn=9#, what is #(m+n)^2#?

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Answer 1 · 2017-07-16T14:16:04

#(m+n)^2=30#

The first thing we should do is expand #(m+n)^2# using the perfect square formula.

#(m+n)^2 = m^2+n^2+2mn#

#m^2+n^2 = 12#

#mn=9 rArr 2mn=18#

#therefore (m+n)^2 = 12+18=30#

Answer 2 · 2017-07-16T14:21:20

#30#

#"expand " (m+n)^2#

#rArr(m+n)^2=m^2+2mn+n^2#

#"evaluate using the given statements"#

#rArr(m+n)^2=12+(2xx9)=30#