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a) M = 8ab;
b) N = [ ( 3 a + + 2 ) + ( 1 – 2 b ) ] 2 = ( 3 a – 2 b + 3 ) 2 .
= \(\left(3a-1\right)^2\) + \(2\left(3a-1\right)\left(3a+1\right)\) + \(\left(3a-1\right)^2\)
= \(\left(3a-1+3a+1\right)^2\)
= \(\left(6a\right)^2\)
= \(36a^2\)
\(\left(3a-1\right)^2+2\left(9a^2-1\right)+\left(3a+1\right)^2\)
\(=\left(3a-1+3a+1\right)^2\)
\(=36a^2\)
\(7a\left(3a-5\right)+\left(2a-3\right)\left(4a+1\right)-\left(6a-2\right)^2\)
\(=21a^2-35a+8a^2+2a-12a-3-36a^2+24a-4\)
\(=-7a^2+4a-7\)
a: \(P=\dfrac{2}{3x+2}-\dfrac{1}{3x-2}+\dfrac{4}{9x^2-4}\)
\(=\dfrac{6x-4-3x-2+4}{\left(3x+2\right)\left(3x-2\right)}=\dfrac{3x-2}{\left(3x+2\right)\left(3x-2\right)}=\dfrac{1}{3x+2}\)
\(=\left(3a-1\right)^2+2\left(3a-1\right)\left(3a+1\right)+\left(3a+1\right)^2\\ =\left(3a-1+3a+1\right)^2=\left(6a\right)^2=36a^2\)