4х²-14х+6=0
D=(-14)²-4•4•6=196-96=100
x1=-(-14)-√100/2•(-14)=14-10/-28=-4/28=-1/7
x2=-(-14)+√100/2•(-14)=14+10/-28=-24/28=-6/7
Ответ: х1=-1/7; х2=-6/7
tn(2x-π/4)=-1,x≠3π/8+kπ/2,k€z
2x-π/4=arctan(-1)
2x-π/4=-π/4
2x-π/4=-π/4+kπ,k€z
2x=kπ,k€z
x=kπ/2,k€z,x≠3π/8+kπ/2,k€z
x=kπ/2,k€z
Ответ:x=kπ/2,k€z
3(5х+4) + 11= 15х + 12 +11= 15х= - 23; х= приблизительно -1,5