[tex] -3x^{2} +7x+45=(x+6) ^{2} [/tex]

-3x^2+7x+45=(x+6)^2-3x^2+7x+45=x^2+12x+36-4x^2-5x+9=0D=25+16*9=13x1= -1x2=20/6

-3х^2+7х+45=(х+6)^2-3х^2+7х+45=х^2+12х+36х^2+12х+36+3х^2-7х-45=04х^2+5х-9=0д=25-4×4×(-9)=169х1=(-5-13)/2×4=-18/8=-2 1/4х2=(-5+13)/2×4=1