Question

Дорожіть, будь ласка. Завдання на фото:

Answer 1

Ответ:

1

Объяснение:

a=1 33/40=73/40, b=0,625=625/1000=5/8, c=3,2=32/10=16/5

((1/a +1/(b+c))÷(1/a -1/(b+c)))÷(1 +(b²+c²-a²)/(2bc))=(2bc)/(a-b-c)²

1) 1/a +1/(b+c)=(b+c+a)/(a(b+c))

2) 1/a -1/(b+c)=(b+c-a)/(a/b+c))

3) (b+c+a)/(a(b+c)) ÷(b+c-a)/(a(b+c))=(a+b+c)/(a(b+c)) ·(a(b+c))/(-a+b+c)=(a+b+c)/(b+c-a)

4) 1 +(b²+c²-a²)/(2bc)=(2bc+b²+c²-a²)/(2bc)=((b+c)²-a²)/(2bc)=((b+c-a)(b+c+a))/(2bc)

5) (a+b+c)/(b+c-a) ÷((b+c-a)(b+c+a))/(2bc)=(a+b+c)/(b+c-a) ·(2bc)/((b+c-a)(a+b+c))=(2bc)/(-a+b+c)²=(2bc)/(a-b-c)²

(2bc)/(a-b-c)²=(2·5/8 ·16/5)/(73/40 -5/8 -16/5)²=(2·2)/(73/40 -25/40 -128/40)²=4/(-80/40)²=(2/(-2))²=(-1)²=1