Question

Помогите пожалуйста

Answer 1

4) a) пусть 7a-11=x, тогда
x² -25 = (x -5)(x +5) =
=(7a -11 -5)(7a -11 +5) =
= (7a -16)(7a -6)

b) b+2=y
4b² -y² =(2b -y)(2b +y) =
=(2b-(b+2)(2b+b+2)=
(2b-b-2)(3b+2)=(b-2)(3b+2)

в) 12c-7d=x, 9c+4d=y
x²-y²=(x-y)(x+y)=
(12c-7d-(9c+4d)(12c-7d+9c +4d)=
(12c-7d-9c-4d)(21c-3d)=
=(3c-11d)(21c-3d)