1)bn=b1*q^(n-1)
200=b1*10^5 b1=200/100000=0.002
2)sn=(b1-bn*q)/(1-q)
sn=(0.002-200*10)/(1-10)=(-1999,998)/(-9)=222,222
1) x-y=2
x^2-xy+y^2=7
x=2+y
(2+y)^2 - y(2+y)+y^2=7
y^2+2y+4=7
y^2+2y-3+0
D=4-4*(-3)=16
y1 = -2+4/2 =1
y2 = -2-4/2 = -3
x1 = 2+1= 3
x2 = 2-3= -1
Y=kx+b
15=0k+b
b=15
y=kx+b
0=-3/2k+b
0=-3/2k+15 *2
-3k+30=0
-3k=-30
k=10