Đáp án:
a) |2x - $\dfrac{1}{3}$| +107
Vì |2x - $\dfrac{1}{3}$| ≥ 0
⇒ |2x - $\dfrac{1}{3}$| +107 ≥ 107
Dấu ''='' xảy ra ⇔ |2x - $\dfrac{1}{3}$| = 0
⇔ 2x - $\dfrac{1}{3}$ = 0
⇔ 2x = $\dfrac{1}{3}$
⇔ x = $\dfrac{1}{6}$
Vậy Min |2x - $\dfrac{1}{3}$| +107 = 107 ⇔ x = $\dfrac{1}{6}$
b)(x - $\dfrac{3}{4}$)² +2021
Vì (x - $\dfrac{3}{4}$)² ≥ 0
⇒ (x - $\dfrac{3}{4}$)² +2021 ≥ 2021
Dấu ''='' xảy ra ⇔ (x - $\dfrac{3}{4}$)² = 0
⇔ x - $\dfrac{3}{4}$ = 0
⇔ x = $\dfrac{3}{4}$
Vậy Min (x - $\dfrac{3}{4}$)² +2021 = 2021 ⇔ x = $\dfrac{3}{4}$