(x2-4x+11)(x4-8x2+21)=35
((2-4)x+11)(x(4-8-2)+21)=35
(-2x+11)(x(-6)+21)=35
(-2x.x(-6))+(11.21)=35
-8x+231=35
-8x=35-231
-8x=-196
x=-196:(-8)
x=24.5
đúng ko pn
\(\left(x^2-4x+11\right)\left(x^4-8x^2+21\right)=35\)
\(\Leftrightarrow\left(x-2\right)^2\left(x^4-x^2+28x+49\right)=0\)
\(\Leftrightarrow x=2\)
\(\left(x^2-4x+11\right)\left(x^4-8x^2+21\right)=35\)
\(\Leftrightarrow\left(\left(x-4\right)x+11\right)\left(x^4-8x^2+21\right)=35\)
\(\Leftrightarrow x=2\)
VT=(x^2-4x+4+7)(x^4-8x^2+16+5)=[(x-2)^2+7].[(x^2-4)^2+5] >/ 7.5 = 35
đẳng thức xảy ra nên x=2 là nghiệm của pt