mohon dibantu yaa .. mksh

jawab
persamaan garis singgung

x² + y² -2x + 4y - 21= 0
(x - 1)² + (y +2)²= 21 + 1 + 4
(x - 1)²  +(y+2)² = 26

m sejajar  x+ 5y = 15
m = - 1/5
pers gasing  y-b = m(x - a) +- r√(m²+1)
y + 2 = -1/5 (x -1) +- √26. √26/25
y + 2 = - 1/5 x + 1/5 +- 26/5

y+2 = - 1/5x + 1/5 + 26/5 ..kalikan 5
5y +10 = -x + 1 + 26
x + 5y = 27-10
x + 5y = 17

y+2 = -1/5 x +1/5 - 26/5...kalikan 5
5y +10 = - x + 1 -  26
5y + x = -25- 10
x + 5y = -35