4x-8 - 20+5x = 6

4x+5x = 6+20+8

9x = 34

\(x=\frac{34}{9}\)

\(2x^2+2y^2-2xy+2x+2y+2=0\)

\(\left(x^2+2xy+y^2\right)+\left(x^2+2x+1\right)+\left(y^2+2y+1\right)=0\)

(x^2+3x+2)(x^2+7x+12)+1

=(x²+x+2x+2)(x²+3x+4x+12)+1

=[x.(x+1)+2.(x+1)][x.(x+3)+4.(x+3)]+1

=(x+1)(x+2)(x+3)(x+4)+1

=[(x+1)(x+4)][(x+2)(x+3)]+1

=(x²+5x+4)(x²+5x+6)+1

=(x²+5x+4)[(x²+5x+4)+2]+1

=(x²+5x+4)²+2(x²+5x+4)+1

=(x²+5x+4+1)²

=(x²+5x+5)²

376

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