3√45-√125+√80 = 3√(9*5)-√(25*5)+√(16*5) = 3*3√5-5√5+4√5 = 9√5-√5 = 8√5
Поделим на cos²x≠0
3tg²x-13tgx+4=0
tgx=a
3a²-13a+4=0
D=169-48=121
a1=(13-11)/6=1/3⇒tgx=1/3⇒x=arctg1/3+πn
a2=(13+11)/6=4⇒tgx=4⇒x=arctg4+πn
ОДЗ
cosx≤0⇒x∈[π/2+2πn;3π/2+2πn,n∈z]
cosx=0⇒x=π/2+2πn,n∈z U x=3π/2+2πn,n∈z
tg²x+tgx=0
tgx(tgx+1)=0
tgx=0⇒x=πn,n∈z+ОДЗ⇒x=π+2πn,n∈Z
tgx=-1⇒x=-π/4+πn,n∈z +ОДЗ⇒x=3π/4+2πn,n∈z
А) (4-x)*(4+x)
b) (3a-2b)(3a+2b)
в) (x-3)^2
г) (a+2b)^2
д) (a-2)(a^2+2a+4)
е) a(a^2-4)=a(a-2)(a+2)
ж) (a^2-9)(a^2+9)=(a-3)(a+3)(a^2+9)