Question

e sẽ tick sau

Answer 1

Câu 9:

a: \(u_1-u_3+u_5=15\)

=>\(u_1-u_1-2d+u_1+4d=15\)

=>\(u_1+2d=15\)

=>\(2u_1+4d=30\)

\(u_1+u_6=27\)

=>\(u_1+u_1+5d=27\)

=>\(2u_1+5d=27\)

=>\(2u_1+5d-2u_1-4d=27-30\)

=>d=-3

\(u_1=15-2d=15-2\cdot\left(-3\right)=21\)

=>Đúng

b: Sai

c: \(u_{11}=u_1+10d=21+10\cdot\left(-3\right)=21-30=-9\)

=>Đúng

d: \(u_{2024}=u_1+2023d=21+2023\cdot\left(-3\right)=-6048\)

=>Đúng