30a-5(a+3)=30-5(a^2+6a+9)=30a-5a^2-30a-45=-5a^2-45=-5(a^2+9)
-5((√3)^2+9)=-5(3+9)=-5*12=-60
Как-то так
√3·cos²15°- √3·sin²15°=<span>√3</span>·<span>(cos</span>²<span> 15°- sin</span>²<span> 15°) =</span>√3·сos(2·15⁰)=√3·cos30⁰=√3·√3/2=3/2=1,5
(x²-4x)²-(x²-4x+4)-16≤0
(x²-4x)²-(x²-4x)-20≤0
x²-4a=a
a²-a-20≤0
a1+a2=1 U a1*a2=-20
a1=-4 u a2=5
-4≤a≤5
{x²-4x≥-4 (1)
{x²-4x≤5 (2)
(1) x²-4x+4≥0
(x-2)²≥0⇒x-любое
(2) x²-4x-5≤0
x1+x2=4 u x1*x2=-5⇒x1=-1 U x2=5
x∈[-1;5]
3 ( 4 (5x+2) - 4 (5x+2-7) )
3 ( 4 (5x+2) - 4 (5x-5) )
3 ( 20x + 8 - 20x + 20 )
60x + 24 - 60x + 60
24 + 60
84
1) cos(x/2-π/12)=0
x/2-π/12=π/2 + πk, k∈Z
x/2=π/12 + π/2 + πk
x/2= π/12 + 6π/12 + πk
x/2 = 7π/12 + πk
x= 2(7π/12 + πk)
x=7π/6 + 2πk, k∈Z
2) sin(x-π/3)+1=0
sin(x-π/3)= -1
x-π/3= -π/2 + 2πn, n∈Z
x=π/3 - π/2 + 2πn
x=2π/6 - 3π/6 + 2πn
x= - π/6 + 2πn, n∈Z
Ответ: 7π/6 + 2πk, k∈Z;
- π/6 + 2πn, n∈Z