-5x^2+2x+16=(x-2)^2
-5x^2+2x+16 =x^2-4x+4
-6x2 + 6x + 12 = 0
Делим на 6:
-x2 + x + 2 = 0
D = b2 - 4ac
D = 1 + 8 = 9 = 3^2
x1,2 = -b ± √D/2a
x1 = -1 + 3/-2 = - 2/2= -1
x2 = -1 - 3/-2= 4/2 = 2
ответ: x1 = -1; x2 = 2
7-5(x+6)=-3(8-x)
7-5x-30=-24+3x
-5x-3x=-24-7+30
-8x=-31+30
-8x=-1
x=0.125
2x-3=0.5(x-1)+2
2x-3=0.5x-0.5+2
2x-0.5x=2+3-0.5
1.5x=4.5
x=3
1) -5x^2+2x+16=x^2-4x+4
-5x^2+2x+16-x^2+4x-4=0
-6x^2+6x+12=0 |:(-6)
x^2-x-2-0
D=1-4*1*(-2)=1+8=9
x1=1-3/2=-2/2=-1
x2=1+3/2=4/2=2
2) 7-5x-30=-24+3x
7-5x-30+24-3x=0
-8x=-1
x=1/8
3) 2x-3=0,5x-0,5+2
2x-0,5x=2-0,5+3
1,5x=4,5
x=3