Question

14x+15x+16x+...+42x=812​

Answer 1

X( 14+15+16+..+42)= 812

*aflam nr de termeni:

42-14+1= 42-13= 29

*conform sumei lui gauss:

x[(u-p) nr t]= 812

x( 28×29)=812

X×812=812

=>x= 812:812

=>x=1

u= ultimul termen

p= primul termen

nr t= nr de termeni