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(5^2)^3*5^-6=5^6*5^-6=5^0=1
1) 5x^2(-3x)^2=5x^2*9x^2=45x^4
2) <span>(2х-1)^2-(2х-1)(2х+1)=(2x-1)((2x-1)-(2x+1))=(2x-1)(-2)=-4x+2=2-4x</span>