Question

преоброзуйте в дробь 8 класс,помогите срочно надо

Answer 1

а)
$frac{a+4}{4a} - frac{a-2}{a^2} = frac{a(a+4)}{4a*a} - frac{4(a-2)}{a^2*4} = frac{a(a+4)- 4(a-2)}{4a^2} = \ frac{a^2+4a- 4a+8}{4a^2} = frac{a^2+8}{4a^2}$

б)
$frac{3x}{x+3}+ frac{3x}{x-3}= frac{3x(x-3)}{(x+3)(x-3)}+ frac{3x(x+3)}{(x-3)(x+3)}= \ frac{3x(x-3)+ 3x(x+3)}{(x-3)(x+3)}= frac{3x((x-3)+(x+3))}{(x-3)(x+3)}= frac{3x(x-3+x+3)}{(x-3)(x+3)}= \ frac{3x2x}{(x-3)(x+3)}=frac{6x^2}{x^2-9}$


в)
$frac{9x^2}{3xy-y^2}- frac{y}{3x-y} = frac{9x^2}{y(3x-y)}- frac{y}{3x-y} = \ frac{9x^2}{y(3x-y)}- frac{y*y}{y(3x-y)} =frac{9x^2-y^2}{y(3x-y)} =frac{(3x)^2-y^2}{y(3x-y)} = \ frac{(3x-y)(3x+y)}{y(3x-y)} = frac{3x+y}{y}$

г)
$a-3b+ frac{6ab}{a-3b}= a* frac{a-3b}{a-3b}-3b*frac{a-3b}{a-3b}+ frac{6ab}{a-3b}= \ frac{a(a-3b)-3b(a-3b)+6ab}{a-3b} =frac{a^2-3ab-3ab+9b^2+6ab}{a-3b} =frac{a^2+9b^2}{a-3b}$