Question

Срочно помогите, даю 80 балов. Скоротiть дрiб

Answer 1

$\displaystyle\bf\\1)\\\\\frac{15x^{2} -3x}{2-10x} =\frac{3x\cdot(5x-1)}{2\cdot(1-5x)} =-\frac{3x\cdot(5x-1)}{2\cdot(5x-1)} =-\frac{3x}{2} =-1,5x\\\\\\2)\\\\\frac{z^{2}-49 }{z^{2} +14z+49} =\frac{z^{2} -7^{2} }{z^{2} +2\cdot z\cdot 7+7^{2} } =\frac{(z+7)(z-7)}{(z+7)^{2} } =\frac{z-7}{z+7}$