Решение смотри на фотографии
N°1
а)(a+5)²=a²+2*a*5+5²=a²+10a+25
б)(3y-x)²=(3y)²-2*3y*x+x²=9y²-6xy+x²
в)(2b-1)(2b+1)=(2b)²-1²=4b²-1
г)(4a+3b)(4a-3b)=(4a)²-(3b)²=16a²-9b²
N°2
а)b²-16=b²-4²=(b+4)(b-4)
б)a²+6a+9=a²+2*a*3+3²=(a+3)²
в)49в²b⁴-100c⁴=(7вb²)²-(10c²)²=(7вb²+10c²)(7вb²-10c²)
г)(x+1)²+(x-1)²=x²+2*x*1+1²+x²-2*x*1+1²=x²+2x+1+x²-2x+1=2x²+2
N°3
(a-3)²-3a(a-2)=a²-2*a*3+3²-3a²+6a=a²-6a+9-3a²+6a=-2a²+9
(512⁵ * 2⁻³) / (16⁰ * 2⁻²) = ((2⁹)⁵ * 2⁻³) / (1 * 2⁻²) = (2⁴⁵ * 2⁻³) / (2⁻²) = ((2⁴²) / (2⁻²) = 2⁴⁴
2cos (x + ) cos ( x - ) =1/2
cos2x+cos2П/3=1/2
cos2x-1/2=1/2
cos2x=1
x=Пk