[Toán 6] Giá trị tuyệt đối,Chứng Minh

N

notthinginmyeyes

Last edited by a moderator:
S

soccan

$1)\\
(5x-3)^2 \ge 49\\
\longleftrightarrow 25x^2-30x-40 \ge 0\\ \longrightarrow (x-2)(5x+4) \ge 0$
do đó x−2≥0∧5x+4≥0∨x−2≤0∧5x+4≤0x-2 \ge 0 \wedge 5x+4 \ge 0 \vee x-2 \le 0 \wedge 5x+4 \le 0
suy ra x∈[−45;2]x \in\left [ -\dfrac{4}{5};2 \right ]
 
You must log in or register to reply here.
Top Bottom