4x^2-12x+9y^2+30y+35
=(4x^2-12x+9)+(9y^2+30y+25)+35-9-25
=(2x-3)^2+(3y+5)^2+1,
(2x-3)^2+(3y+5)^2是非负数,所以4x^2-12x+9y^2+30y+35的最小值为1.