Question

resolva as seguintes questões: a) X elavado a 2 - 10x +21=0 b) X elevado a 2 - 11 x +30 =0.

Answer 1

x² -10x +21 = 0 

a= 1 b= -10  c= 21

Δ = b² -4 .a .c
Δ = (-10)² -4 . 1 . 21
Δ = 100 - 84
Δ = 16

x =-b+- √Δ /2a
x = - (-10) + - √16/2.1
x = 10 + - 4/2

x' = 10 +4/2 = 14 /2 = 7
x" = 10 -4 /2 = 6/2=3




x² - 11 x +30 =0.
a = 1  b = -11  c = 30

Δ= b² -4 .a.c 
Δ=(-11)² -4 .1 . 30
Δ=  121 - 120 
Δ= 1

x = -b+-√Δ/2a
x -(-11) + - √1/2.1
x = 11 + - 1/2

x'= 11 +1/2 = 12/2 = 6

x" 11 -1 /2 = 10 /2 = 5