Answer 1

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

Answer 2

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