Ex 26, doar pct 1
Dau multe puncte!

Răspuns:
Explicație pas cu pas:
1/(4k - 3)(4k + 1) = 1/4 (1/(4k - 3) - 1 /(4k + 1))
1/(4k - 3)(4k + 1) = 1/4 (4k + 1 - 4k + 3)/(4k - 3)(4k + 1)
1/(4k - 3)(4k + 1) = 4/4(4k - 3)(4k + 1) se simplifica cu 4
1/(4k - 3)(4k + 1) = 1/(4k - 3)(4k + 1) adevarat