Toán cực khó

N

ngobin3

B

braga

Bài 2 dùng xét khoảng cho nhanh :)

[TEX]+, \ x \leq -\frac{3}{4}[/TEX]

[TEX]\Leftrightarrow -(4x+3)+(x-1)=7 \Leftrightarrow -4x-3+x-1=7 \Leftrightarrow -3x=11 \Rightarrow x=\frac{-11}{3}[/TEX]

[TEX]+, \ \frac{3}{4}<x \leq 1[/TEX]

[TEX]\Leftrightarrow 4x+3+x-1=7 \Leftrightarrow 5x=5 \Rightarrow x=1[/TEX]

[TEX]+, \ x>1[/TEX]

[TEX]\Leftrightarrow 4x+3-x+1=7 \Leftrightarrow 3x=3 \Rightarrow x=1[/TEX]
 
Last edited by a moderator:
You must log in or register to reply here.
Top Bottom