\(x\left(x+10\right)-x\left(x+2\right)=30\\ x^2+10x-x^2-2x=30\\ 8x=30\\ x=3,75\)

\(\left(x-1\right)\left(x+1\right)\\ =x^2-1\)

\(\left(x-2\right)\left(x^2+2x+4\right)\\ =x^3-2^3\\ =x^3-8\)

\(\left(2p-4p\right)^2+4p-8p+1\\ =2p^2-16p^2+16p^2-4p+1\\ =2p^2-4p+1\\ =\left(2p-1\right)^2\)

\(\left(2x-1\right)\left(3x+2\right)\left(3-x\right)\\ =\left(6x^2+4x-3x-2\right)\left(3-x\right)\\ =18x^2-6x^3+12x-4x^2-9x+3x^2-6+2x\\ =-6x^3+17x^2+5x-6\)

\(\left(x+5\right)\left(x^2-5x+25\right)\\ =x^3+5^3\\ =x^3+125\)