Bài 1: Rút gọn
a-4+ cbh 16-8a+a^2 (a>4)
a) x^2-3/x^2+2xcbh3+3;x^2-2xcbh15+15/x^2-15;4x^2-6/4x^2-4xcbh6+6
b) a^2+2acbh8+8/a^2-8;9x^2-15/9x^2-6.xcbh15+15;a^2-2acbh7+7/a^2-7
Bài 2: Giải pt
a) cbhx^2=8;cbhx^2=|-10|
b) cbh9x^2=2x+1
cbh x^2-6x+9=3x-1
c)cbh x^4=7
d) x^2-2cbh13x+13=0
4x^2-4xcbh5+5
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