Tolong dijawab berserta caranya

f(x) = bx²+4x-3 = 0
f(1) = b(1)²+4(1)-3 = 0
b+1=0
b=-1

-x²+4x-3=0
x²-4x+3=0
(x-3)(x-1)=0
x1=1, x2=3

persamaan kuadrat baru
x1+x2=2+4=6
x1.x2=2×4=8

x² - (x1+x2)x + (x1.x2) = 0
x² - 6x + 8 = 0