Question

Дайте ответ хотя бы на первое пожалуйста

Answer 1

$\displaystyle\bf\\5)\\\\\Big(\frac{2}{7} x^{4} -9y^{2} k\Big)\Big(\frac{2}{7} x^{4} +9y^{2} k\Big)=\Big(\frac{2}{7} x^{4} \Big)^{2} -\Big(9y^{2}k \Big)^{2} =\frac{4}{49} x^{8} -81y^{4}k^{2} \\\\\\6)\\\\(x-1)^{2} -(x-3)^{2} =0\\\\(x-1-x+3)\cdot(x-1+x-3)=0\\\\2\cdot(2x-4)=0\\\\2x-4=0\\\\2x=4\\\\x=2$