Question

помогитееее надо прям
какой сможете

Answer 1

2.
$frac{3}{a} + frac{a-3}{a+5} = frac{3(a+5)+a(a-3)}{a(a+5)} = frac{3a+15+a^2-3a}{a(a+5)} = frac{a^2+15}{a^2+5a} \ \ frac{2x^2}{x^2-4} - frac{2x}{x+2} = frac{2x^2 - 2x(x-2)}{(x-2)(x+2)} = frac{2x^2-2x^2+4x}{(x-2)(x+2)} = frac{4x}{x^2-4}$

3.
$frac{y^2 - 6y + 9}{y^2 - 9} : frac{10y - 30}{y^2+3y} = frac{(y-3)^2}{(y-3)(y+3)} : frac{10(y-3)}{y(y+3)} = frac{y-3}{y+3} : frac{10(y-3)}{y(y+3)} = \ \ = frac{y-3}{y+3} * frac{y(y+3)}{10(y-3)} = frac{y}{10} = frac{1}{10}*y = 0.1y \ \ y = 70 \ 0.1 * 70 = 7$

4.
x/y  = a  
x  = ay

y/z  = 1/a
1*z = ay
z=ay

x/z  = ay/ay
x/z  = 1