解一下1.3.5题谢谢

网友回答

解(1)x^2+10x+9=0
(x+1)(x+9)=0
∴x=-1或x=-9
(2)3x^2+6x-4=0
△=b^2-4ac=36+3×4×4=84
∴x=(-6+√84)/6=-1+√21/3
或x=(-6-√84)/6=-1-√21/3
(5)x^2+4x-9=2x-11
x^2+2x+2=0
△=b^2-4ac=4-2×8×1