Question

a)N=1 +3+5+7+...+999


b)2×25-5×[9+5-3×(2x-
1)]=25


c) (3249-1)×(3249-2)×
( 3249-3)×...×(3249-3249)


Urgent!

Answer 1

A)N=1 +3+5+7+...+999 = (1+999)*500/2=250 000
a1=2n-1=1
1=2*1-1
an=999
2*n-1=999
2n=1000
n=500



b)2×25-5×[9+5-3×(2x-1)]=25
50-5×[14-3×(2x-1)]=25
50-25=5×[14-3×(2x-1)]
5×[14-3×(2x-1)]=25
14-3×(2x-1)=25:5
14-3×(2x-1)= 5
14-5= 3×(2x-1)
3×(2x-1)=9
2x-1=9:3
2x-1=3
2x=3+1
2x=4
x=2

c) (3249-1)×(3249-2)×( 3249-3)×...×(3249-3249)=

=2348*3247*3246*.....*0=0

orice nr. inmultit cu 0 = 0