Question

Спростити 1) (а-3)(а+3)=
2) (x-у)(х+у) =
3) (а-5)(а+5)-2а (4+а)=
4) (4х-3)(4х+3)+(3х+4)(4-3х)=
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Answer 1

Ответ:

$1) (a-3)(a+3)=a^2-9\\2) (x-y)(x+y)=x^{2} -y^2\\3) (a-5)(a+5)-2a(4+a)=a^2-25-8a-2a^2=-a^2-25-8a\\4) (4x-3)(4x+3)+(4+3x)(4-3x)=16x^{2} -9+16 -9x^{2} =7x^{2} +7$