Question

[Nguyễn Phương Chi]

Tìm giá trị nhỏ nhất:

a) A= \(\left|3,4-x\right|+1,7\)

b) B= \(\left|x+48\right|3,5\)

c) C= \(\left|4x-3\right|+\left|5y+7,5\right|+17,5\)

Answer 1

[Nguyễn Hoàng Minh]

\(a,A=\left|3,4-x\right|+1,7\ge1,7\)

Dấu \("="\Leftrightarrow3,4-x=0\Leftrightarrow x=3,4\)

\(c,C=\left|4x-3\right|+\left|5y+7,5\right|+17,5\ge17,5\)

Dấu \("="\Leftrightarrow\left\{{}\begin{matrix}4x-3=0\\5y+7,5=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{3}{4}\\y=-\dfrac{3}{2}\end{matrix}\right.\)