Question

[Học đi]

giúp mk nhé

Bai 1 :Cho M=-3.(5+17)+5.(3-17)

N=(-15+1).(-15+2)...(-15+100)

So sánh M và N

Bài 2

P1=(-3).7.(-2).(-13)

P2=(-1).(-2).(-3).(-4).5

So sanh P2 với P1 mà không thực hiện phép tính.

Bài 3:tìm x thuộc Z

a)x.(x-1)=0

b)(x-3).(x+4)=0

c)(2x-4).(x+2)=0

d)(x+1)^2.(x-2)^2=0

e) x(x+1).(x+2)^2.(x+3)^3=0

f)(x-9)^5.(x-5)^8=0

g)x(x+100)^10.(x+2000)^20.(x+300)^300=0

h)(x-2)^2=0

Answer 1

[Đức Minh]

Bài 2: - Xét dấu :

P1 : (-).(+).(-).(-) -> Kết quả cuối cùng là số âm.

P2 : (-).(-).(-).(-).(+) -> Kết quả cuối cùng là số dương.

===> P1 < P2.

Bài 3 :

a) \(x\cdot\left(x-1\right)=0\)

\(\Rightarrow\left[\begin{matrix}x=0\\x-1=0\end{matrix}\right.\rightarrow\left[\begin{matrix}x=0\\x=1\end{matrix}\right.\)

b) \(\left(x-3\right)\cdot\left(x+4\right)=0\)

\(\left[\begin{matrix}x-3=0\\x+4=0\end{matrix}\right.\rightarrow\left[\begin{matrix}x=3\\x=-4\end{matrix}\right.\)

c) \(\left(2x-4\right)\cdot\left(x+2\right)=0\rightarrow\left[\begin{matrix}2x-4=0\\x+2=0\end{matrix}\right.\rightarrow\left[\begin{matrix}x=2\\x=-2\end{matrix}\right.\)

d) \(\left(x+1\right)^2\cdot\left(x-2\right)^2=0\rightarrow\left[\begin{matrix}x+1=0\\x-2=0\end{matrix}\right.\rightarrow\left[\begin{matrix}x=-1\\x=2\end{matrix}\right.\)

e) \(x\cdot\left(x+1\right)\cdot\left(x+2\right)^2\cdot\left(x+3\right)^3=0\)

\(\Rightarrow\left[\begin{matrix}x=0\\x+1=0\\x+2=0\\x+3=0\end{matrix}\right.\rightarrow\left[\begin{matrix}x=0\\x=-1\\x=-2\\x=-3\end{matrix}\right.\)

f) \(\left(x-9^5\right)\cdot\left(x-5\right)^8=0\)

\(\Rightarrow\left[\begin{matrix}x-9=0\\x-5=0\end{matrix}\right.\rightarrow\left[\begin{matrix}x=9\\x=5\end{matrix}\right.\)

g) \(x\cdot\left(x+100\right)^{10}\cdot\left(x+2000\right)^{20}\cdot\left(x+300\right)^{3000}=0\)

\(\Rightarrow\left[\begin{matrix}x=0\\x+100=0\\x+2000=0\\x+300=0\end{matrix}\right.\rightarrow\left[\begin{matrix}x=0\\x=-100\\x=-2000\\x=-300\end{matrix}\right.\)

h) \(\left(x-2\right)^2=0\rightarrow x=2\)