Если один катет =х. то второй =0,2х. Площадь=1/2*х*0,2х=90, 0,2*х²=45. х²=225, х=15.
Вторая сторона =0,2*15=3
Периметр=2*(3+15)=36
![b_5=b_1*(\frac{1}{2})^4=\frac{1}{8}](https://tex.z-dn.net/?f=b_5%3Db_1%2A%28%5Cfrac%7B1%7D%7B2%7D%29%5E4%3D%5Cfrac%7B1%7D%7B8%7D)
![b_1*\frac{1}{16}=\frac{1}{8}](https://tex.z-dn.net/?f=b_1%2A%5Cfrac%7B1%7D%7B16%7D%3D%5Cfrac%7B1%7D%7B8%7D+)
![b_1=2](https://tex.z-dn.net/?f=b_1%3D2)
![S_3=\frac{2(\frac{1}{2})^3-1)}{\frac{1}{2}-1}=\frac{2(\frac{1}{8}-1)}{-\frac{1}{2}}=-4*(-\frac{7}{8})=\frac{7}{2}=3,5](https://tex.z-dn.net/?f=S_3%3D%5Cfrac%7B2%28%5Cfrac%7B1%7D%7B2%7D%29%5E3-1%29%7D%7B%5Cfrac%7B1%7D%7B2%7D-1%7D%3D%5Cfrac%7B2%28%5Cfrac%7B1%7D%7B8%7D-1%29%7D%7B-%5Cfrac%7B1%7D%7B2%7D%7D%3D-4%2A%28-%5Cfrac%7B7%7D%7B8%7D%29%3D%5Cfrac%7B7%7D%7B2%7D%3D3%2C5)
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1.а)6cd ∙ 2ac=2с(3d∙a)
б)<span>4m ∙ (–5n) ∙ (–8k)=160mnk
2.</span><span>4 – 12b – 2a + 5b – a=4-7b-3a
3.x+3x+x-150
4.</span><span>11n – (7n – 1) – 6n + 8 при n = 16
11 </span>∙ 16 - (7∙16-1)-6∙16+8=176-111-88=23
5. <span>4 (2а – c) – 5(а + 3c)= 8a-4c-5a-15c = 3a-19c
6.</span>у – х – 1= <span>ab – 1-ab-1-1= -3
7.</span><span>х (у + z) – y (x + z) – z (x – y)=xy+xz-yx-yz-zx+zy=0
8.Извини , не знаю Если пойму , отпишусь.</span>
(a+3b)(a+b+2)-(a+b)(a+3b+2)=
(а*а + а*b + а*2 +3b*а +3b*b + 3b*2) - (а*а +а*3b + а*2 +b*а + b*3b + b*2)=
(а² + аb +2а +3bа + 3b² +6b) - (а²+3аb + 2а +аb +3b²+2b)=
(а² + 4аb +2а + 3b² +6b) - (а²+4аb + 2а +3b²+2b)=
а² + 4аb +2а + 3b² +6b - а²-4аb - 2а -3b²- 2b=
6b - 2b=
=4b
Ответ: 4b