Question

1) (n-3)²-(n+2)*(n-2)
И то что на фото.

Answer 1

1) n²-6n+9-(n²-4)=n²-6n+9-n²+4=-6n+13
7) ((x+y)+1)((x+y)-1)=(x+y)²-1=x²+2xy+y²+1
8) $frac{ 4^{n}(4 ^{2}-1)* 5^{n} }{ 5^{n}* 3^{n}*15* 3^{-n}* 4^{-n}}= frac{ 4^{n}(16-1) }{3^{n}*15* 3^{-n}* 4^{-n}}= frac{ 4^{n}*15*4^{n} * 3^{n} }{3^{n}*15}= 4^{n+n}= 4^{2n}$
9) $frac{4y}{x(x-3y)}- frac{x}{y(x-3y)} * frac{xy(3y-x)}{ x^{2} -4 y^{2} } = frac{4 y^{2}- x^{2} }{xy(x-3y)}*frac{xy(3y-x)}{ x^{2} -4 y^{2} }=$$- frac{ x^{2}-4 y^{2} }{xy(x-3y)}*frac{-xy(x-3y)}{ x^{2} -4 y^{2} }=1$