Б) x^2-x = a
a^2-15a-100=0
D=15*15+4*100 = 625=25^2
a1 = (15+25)/2=20
a2 = (15-25)/2=-5
x^2-x=20, x^2-x-20=0, D=1+4*20=81 =9^2, x1=(1+9)/2=5, x2=(1-9)/2=-4
x^2-x=-5, x^2-x+5=0, D=1-4*5=-19<0</p>
x=5 или x=-4
В)
3(x^2+x)^2 -10x^2 -10x=48
3(x^2+x)^2 -10(x^2+x)-48=0
x^2+x = a
3a^2-10a-48=0
D=10*10+4*3*48 = 100+576=676=26^2
a1 = (10+26)/6=6
a2 = (10-26)/6=-8/3
x^2+x=6, x^2+x-6=0, D=1+4*6=25 =5^2, x1=(-1+5)/2=2, x2=(-1-5)/2=-3
x^2+x=-8/3, x^2+x+8/3=0, D=1-4*8/3=<0</p>
x=2 или x=-3