Answer:
The discriminant equals to 0
Step-by-step explanation:
We have to remember our discriminant rules;
d > 0, we have 2 real roots
d = 0, we have 1 real root
d < 0, we have 2 complex roots
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You reverse what you did, so first you go 5 units down which makes the coordinates (9,1) then you move 3 units left which then is (6,1). Then you go 4 units up which lets you end out at (6,5).
A = P + I
2a = a + PTR/100
2a = a + 5aT/100
2a = a(1+T/20)
2=1+T/20
T=20 yrs