Question

(3x+1)² = 10(x-1)(x + 1)
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Answer 1

(3x+1)² = 10(x-1)(x + 1)

9x^2+6x+1=10(x^2-1)

9x^2+6x+1=10x^2-10

9x^2+6x+1-10x^2+10=0

-x^2+6x+11=0

x^2-6x-11=0

D= b^2-4ab

D= -6^2-4×1×(-11)= 36+44=80 >0, 2 корня

x1= (b+√D)/2a = (6+√80)/2×1= (6+4√5)/2= 2(3+2√5)/2=3+2√5

x2= (b-√D)/2a= (6-√80)/2×1= (6-4√5)/2=

2(3-2√5)/2=3-2√5