Question

Решите срочно
Даю 20

Answer 1

№1.

а) $\frac{14x^2b^4}{21x^6b^3} =\frac{2b}{3x^4}$; б) $\frac{6x}{2x^2-6x}=\frac{6x}{2x(x-3)} =\frac{3}{x-3}$; в) $\frac{x^2-16}{x-4} =\frac{(x-4)(x+4)}{x-4} =x+4$

№2

а) $\frac{4y-3}{6y}+\frac{y+2}{4y} =\frac{8y-6}{12y} +\frac{3y+6}{12y} =\frac{8y-6+3y+6}{12y} =\frac{11y}{12y} =\frac{11}{12}$

б) $\frac{a}{a+5} -\frac{a}{a-5}=\frac{a(a-5)}{(a+5)(a-5)} -\frac{a(a+5)}{(a+5)(a-5)} =\frac{a(a-5)-a(a+5)}{(a+5)(a-5)} =\frac{a^2-5a-a^2-5a}{(a+5)(a-5)} =-\frac{10a}{a^2-25} =\frac{-10a}{a^2-25}$

№3

$5a+\frac{2b-15a^2}{3a} =\frac{15a^2}{3a} +\frac{2b-15a^2}{3a} =\frac{15a^2+2b-15a^2}{3a} =\frac{2b}{3a} \\a=4,~b=-12\\\frac{2*(-12)}{3*4} =\frac{-24}{12} =-2$