Question

решите
$- \frac{ {x}^{4} \times {x}^{8} }{ {x}^{10} } + 12.8$
при х равен
1) -1
2) 2
3) -3,1​

Answer 1

$\displaystyle\bf\\-\dfrac{x^{4} \cdot x^{8} }{x^{10} } +12,8=-x^{4+8-10} +12,8=-x^{2} +12,8\\\\1)\\\\x=-1 \ \ \Rightarrow \ \ -x^{2} +12,8=-(-1)^{2} +12,8=-1+12,8=11,8\\\\2)\\\\x=2\ \ \Rightarrow \ \ -x^{2} +12,8=-2^{2} +12,8=-4+12,8=8,8\\\\3)\\\\x=-3,1 \ \ \Rightarrow \ \ -x^{2} +12,8=-(-3,1)^{2} +12,8=-9,61+12,8=3,19$