Ответ: (-3;0) (0.75; 45/16)
0,75*(х+8)=2х+1
0,75х+6=2х+1
1,25х=5
х=4
1) 12+5√27-√48= 12+15√3-4√3= 12+11√3
2) (√7-√2)(√7+√2)+√56= √7²-√2²+2√14= 7-2+2√14= 5+2√14
3) (2+√5)(√5-2)= √5²-2²= 5-4= 1
4) √8+√2= 2√2+√2= 3√2
5) (√7-1)*(√7-1)= 7-2√7+1= 8-2√7
6) (√5x-√5y)(√5x-√5y)-5(x+y)= 5x-5√xy+5y-5x-5y= -5√xy
7) 6-3√x/4-x= 3(2-√x)/(2-√x)(2+√x)= 3/(2+√x)
1) -5*x^2-30*x=4*x-12-10
-5*x^2-30*x-4*x+12+10=0
5*x^2+34*x-22=0
2) 3*x^2+9*x-9*x-27=x^2+9*x-8*x-72
3*x^2-x^2-9*x+8*x-27+72=0
2*x^2-x+45=0