a)1-x²= -8

x² =1-(-8)

x² =1+8

x²=9

x²=3²

=>x=3

b)-19-(1-2x)²=2².11

(1-2x)2= -19-4.11

(1-2x)² = -19-44

(1-2x)² = -19+(-44)

(1-2x)²= -63

1²-2x²= -63

1-2x² = -63

2x²  =1-(-63)

2x²  =64

2x²=8²

=>2x=8

=>x=8:2=4
 c)13-|x²|=9

|x²|=13-9

 |x²|=4

  |x²| co hai truong hop xay ra

TH1:x²=4

=>x²=2²

=>x=2

TH2:x²= -4

=> x thuoc tap hop rong