a) A(x) = x² - 4
Xét A(x) = 0 <=> x² - 4 = 0 <=> x² = 4 <=> x = 2
Vậy A(x) = 2
b) B(x) = 3(x - 1)² - 27
Xét B(x) = 0 <=> 3(x - 1)² - 27 = 0 <=> 3(x - 1)² = 27 <=> (x - 1)² = 9 <=> x - 1 = 3 <=> x = 4
Vậy B(x) = 4
c) C(x) = $\frac{x}{4}$ - $\frac{4}{2}$
Xét C(x) = 0 <=> $\frac{x}{4}$ - $\frac{4}{2}$ = 0 <=> $\frac{x}{4}$ = $\frac{4}{2}$
<=> 2x = 16 <=> x = 8
Vậy C(x) = 8
d) D(x) = 1 + (3 - 2x)²
Xét D(x) = 0 <=> 1 + (3 - 2x)² = 0 <=> (3 - 2x)² = - 1 <=> 3 - 2x = 1 <=> - 2x = -2 <=> x = 1
Vậy D(x) = 1
e) E(x) = $\frac{1}{x-1}$ - $\frac{x-1}{1}$
Xét E(x) = 0 <=> $\frac{1}{x-1}$ - $\frac{x-1}{1}$ = 0 <=> $\frac{1}{x-1}$ = $\frac{x-1}{1}$
<=> (x - 1)² = 1 <=> x - 1 = 1 <=> x = 2
Vậy E(x) = 2
e) E(x) = $\frac{1}{2}$ - 2(2x + 1)²
Xét E(x) = 0 <=> $\frac{1}{2}$ - 2(2x + 1)² = 0 <=> - 2(2x + 1)² = - $\frac{1}{2}$
<=> (2x + 1)² = $\frac{1}{4}$
<=> 2x + 1 = $\frac{1}{16}$
<=> 2x = $\frac{-15}{16}$
<=> x = $\frac{-15}{32}$
Vậy E(x) = $\frac{-15}{32}$
f) F(x) = $\frac{1}{x-1}$ - $\frac{x-1}{1}$
Xét F(x) = 0 <=> $\frac{1}{x-1}$ - $\frac{x-1}{1}$ = 0 <=> $\frac{1}{x-1}$ = $\frac{x-1}{1}$
<=> (x - 1)² = 1 <=> x - 1 = 1 <=> x = 2
Vậy F(x) = 2
g) G(x) = $\frac{1}{3}$ +3(- x + 2)²
Xét G(x) = 0 <=> $\frac{1}{3}$ +3(- x + 2)² = 0 <=> 3(- x + 2)² = - $\frac{1}{3}$
<=> (- x + 2)² = $\frac{-1}{9}$ <=> - x + 2 = $\frac{1}{81}$ <=> x = $\frac{161}{81}$
Vậy G(x) = $\frac{161}{81}$
Cho mk ctlhn và vote 5 sao cho mk nha!!!!!
