Cho biểu thức \( A = \sqrt {x + 4\sqrt {x - 4} } + \sqrt {x - 4\sqrt {x - 4} } \)
a) Rút gọn \(A.\)
b) Tìm \(x\) để \(A = 4.\)
A.a) \( A = \left\{ \matrix{2\sqrt {x - 4} \,\,\,\,\,khi\,\,\,\,x \ge 8 \hfill \cr4\,\,\,\,khi\,\,\,4 \le x < 8. \hfill \cr} \right.\)
b) \( x = 8\)
B.a) \( A = \left\{ \matrix{2\sqrt {x - 4} \,\,\,\,\,khi\,\,\,\,x \ge 8 \hfill \cr4\,\,\,\,khi\,\,\,4 \le x < 8. \hfill \cr} \right.\)
b) \( 4 < x \le 8\)
C.a) \( A = \left\{ \matrix{2\sqrt {x - 4} \,\,\,\,\,khi\,\,\,\,x \ge 8 \hfill \cr4\,\,\,\,khi\,\,\,4 \le x < 8. \hfill \cr} \right.\)
b) \( x \geq 8\)
D.a) \( A = \left\{ \matrix{2\sqrt {x - 4} \,\,\,\,\,khi\,\,\,\,x \ge 8 \hfill \cr 4\,\,\,\,khi\,\,\,4 \le x < 8. \hfill \cr} \right.\)
b) \( 4 \le x \le 8\)
a) Rút gọn \(A.\)
b) Tìm \(x\) để \(A = 4.\)
A.a) \( A = \left\{ \matrix{2\sqrt {x - 4} \,\,\,\,\,khi\,\,\,\,x \ge 8 \hfill \cr4\,\,\,\,khi\,\,\,4 \le x < 8. \hfill \cr} \right.\)
b) \( x = 8\)
B.a) \( A = \left\{ \matrix{2\sqrt {x - 4} \,\,\,\,\,khi\,\,\,\,x \ge 8 \hfill \cr4\,\,\,\,khi\,\,\,4 \le x < 8. \hfill \cr} \right.\)
b) \( 4 < x \le 8\)
C.a) \( A = \left\{ \matrix{2\sqrt {x - 4} \,\,\,\,\,khi\,\,\,\,x \ge 8 \hfill \cr4\,\,\,\,khi\,\,\,4 \le x < 8. \hfill \cr} \right.\)
b) \( x \geq 8\)
D.a) \( A = \left\{ \matrix{2\sqrt {x - 4} \,\,\,\,\,khi\,\,\,\,x \ge 8 \hfill \cr 4\,\,\,\,khi\,\,\,4 \le x < 8. \hfill \cr} \right.\)
b) \( 4 \le x \le 8\)
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Hóa Học lớp 12
