895. a) b^2–c^2–b+c=(b–c)(b+c)–(b–c)=(b–c)(b+c–1)
б) (a+b)–(a^2–b^2)=(a+b)–(a–b)(a+b)=
=(a+b)(1–a+b)
в) (а^2–с^2)–(а–с)=(а–с)(а+с)–(а–с)=
=(а–с)(а+с–1)
г) (m–n)–(m^2–n^2)=(m–n)–(m–n)(m+n)=(m–n)(1–m–n)
896. a) a^2(a+1)–(a+1)=(a+1)(a^2–1)=
=(a+1)(a+1)(a–1)=(a+1)^2•(a–1)
б) (b^2–a^2)–c(b–a)=(b–a)(b+a)–c(b–a)=(b–a)(b+a–c)
в) (ab^2–ad^2)+(cd^2–b^2c)=
= a(b^2–d^2)–c(b^2–d^2)=
= (b^2–d^2)(a–c)
г) (x^2y^2–y^2)+(1–x^2)=y^2(x^2–1)–(x^2–1)=(x^2–1)(y^2–1)
sin5x+2sin6x+sin7x=2sin6xcosx+2sin6x=2sin6x(cosx+1)
1) tgx>√3/3
π/6+πn<x<π/2+πn,n∈z
2)ctgx<-1
3π/4+πn<x<π+πn,n∈z
3) cosx≥√2/2
-π/4+2πn≤x≤π/4+2πn,n∈z
4) sinx≤-√3/2
-2π/3+2πn≤x≤-π/3+2πn,n∈z
V=0 откуда т=0 и т=6 время движения точки (т=0 - отпадает).
S=V'=|18-6t|=|18-36|=18