P=2(x+y)=80
S1=x*y
S2=(x+8)(y+2)
S2/S1=1.5,
(x+8)(y+2) / (x*y) = 3/2 (1)
x+y=40
x=40-y, 2*(40-y+8)(y+2)=3*y*(40-y)
(80-2y+16)(y+2)=120y-3y^2
80y+160-2y^2-4y+16y+32-120y+3y^2=0, y^2-28y+192=0, y1=16, y2=12
y1=16, x1=24
y2=12, x2=28
S1=16*24=384, S1'=12*28=336
S2=(24+8)(16+2)=576, S2'=(28+8)(12+2)=504
Ответ:
Ответ:
Объяснение:
1)(x+y)(x-y)=x^2-y^2
2)(n-m)(n+m)=n^2-m^2
3)(k-2)(k+2)=k^2-4
4)(3-c)(3+c)=9-c^2
5)(4-b)(4+b)=16-b^2
6)(a-7)(a+7)=a^2-49
7)(1/7+x)(1/7-x)=1/49-x^2
8)(a-2/9)(a+2/9)=a^2-4/81
9)(5/6+m)(5/6-m)=25/36 - m^2
10)0,4+n)(0,4-m)=0,016-0,4m+0,4n-nm
11)(k+1,1)(k-1,1)=k^2-1,21
12)(d-2,2)(d+2,2)=d^2-4,84²²²²