А.П. а16=а1+д(n-1)
67= 7 +д (16-1)
67 = 7 + 15д
15д= 67-7
15д=60
д=60/15
д=4
(5√5)⁻² - (10√10)⁻²= <u> 1 </u> - <u> 1 </u>= <u> 1 </u> - <u> 1 </u>= <u> 1 </u>- <u> 1 </u>=
(5√5)² (10√10)² 25*5 100*10 125 1000
= <u> 8-1 </u>= <u> 7 </u>= 0,007
1000 1000
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
b/a - b*(1/a - 1/b) = b/a - b/a + 1 = 1
Ответ. 1