(7х"2-5х+3)-(5х"2-4)=7х"2-5х+3-5х"2+4=2х"2-5х+7
1) 2x²-x-3=0
D=1²+4*3*2=25=5²
x₁=(1-5)/(2*2)=-4/4=-1
x₂=(1+5)/(2*2)=6/4=3/2=1.5
2)4x²-17x-15=0
D=17²+4*4*15=289+240=529=23²
x₁=(17-23)/8=-6/8=-0.75
x₂=(17+23)/8=40/8=5
(х+1)/2-5х/12=3/4
6(х+1)-5х=9
6х+6-5х=9
х+6=9
х=9-6
х=3
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