cos11π/12+cos3π/4= 2 cos ((11π/12 + 3π/4)/2)*cos ((11π/12 - 3π/4)/2) = 2cos (5π/6)*cos (π/12) = 2cos 150⁰ cos 15⁰ = 2cos (180⁰ - 30⁰) cos 15⁰ = -2cos 30⁰ cos 15⁰ = -2*√3/2*cos 15⁰ = -√3cos 15⁰
<span>а) f(x)=3x–1
D(y)=R
f`(x)=3
3<0
(-</span>∞ : 3) убыв
(3:+∞) возраст
<span>
б)f(x)=1,5–2x
D(y)=R
f`(x)= -2
-2<0
(-</span>∞;-2) убыв
(-2;+∞) возраст
<span>в)f(x)=x²–6x+5
D(y)=R
f`(x)=2x-6
2x-6<0
2x<6
x<3 x>3
(3</span>;+∞) убыв<span>
(-</span>∞;3) возраст
<span>
г) f(x)=x²–4x
</span><span> D(y)=R
f`(x)= 2x-4
2x-4<0
2x<4
x<2 x>2
(-</span>∞;2) убыв<span>
(2</span>;+∞) возраст<span>
2) </span>а) у=15–2x–х²<span>
D(y)=R
f`(x)=-2-2x
-2-3x<0
-2x<2
x<-1 x>-1
(-</span>∞:-1) убыв<span>
(-1;+</span>∞)возраст
<span>
в) у=х²–6х
</span><span> D(y)=R
f`(x)=2x-6
2x-6<0
2x<6
x<3 x>3
(-</span>∞;3) убыв
(3;+∞) возраст
<span>
г) у=0,25х⁴–0,5х²–1</span>
D(y)=R
f`(x)=x^3-x
x^3-x>0
x(x^2-1)>0
x(x-1)(x+1)>0
(-∞;-1) убыв
(-1;0)возраст
(0;1) убыв
(1;+∞) возраст
<span> √x^15 y^2 = х^7 * у * √х</span>
<span>вот так</span>
A^2+2ab+b^2-9=(a+b)^2-9=(a+b-3)(a+b+3)