64 - 16х+х квадрат +х квадрат+4х+4 = 2хквадрат -12х + 68
1)
y²+100-20y=y²-20y+100=(y+10)²
2)
49x²-42xy+9y²=(7x+3y)²
<span>2cos2x = √3sin(3Π/2+x)
</span><span>2cos2x = -√3cosx
</span>cosx(2cosx +√3)=0cosx=0
x=п/2+пk<span>cosx=-√3/2
x=±(п-п/6)+2пn=±5п/6+2пn k,n €Z</span>