câu 1:tính A=1+2^2+2^4+2^6+…….+2^100

Bạn tham khảo :

$A =1+2^2+2^4+2^6+…….+2^{100}$

$2^2A = 2^2+2^4+2^6+2^8 + … +2^{102}$

$4A -A = (2^2+2^4+2^6+2^8 + … +2^{102}) – (1+2^2+2^4+2^6+…….+2^{100})$

$3A = 2^{102} -1$

$A = \dfrac{2^{102}-1}{3}$