157) \( \frac{\frac{3(a-b)}{a+b} \cdot \frac{2 a b}{a^{2}-b^{2}}}{\frac{a b}{a^{2}+2 a b+b^{2}}}= \)

268. Решите уравнение: \( \begin{array}{l}\text { а) }(y+2)\left(y^{2}-2 y+4\right)-y(y-3)(y+3)=44 \text {; } \\ \text { б) }(m-3)\left(m^{2}+3 m+9\right)-m(m+2)(m-2)=13 \text {; } \\ \text { B) }(3 a+1)\left(9 a^{2}-3 a+1\right)-3 a\left(9 a^{2}+4\right)=25 \text {; }(2 n-1)\left(4 n^{2}+2 n+1\right)-4 n\left(2 n^{2}-5\right)=21 \text {. }\end{array} \).

Evaluate the following function. Your answer should be an integer. \( f(x)=-3^{2 x-2} \), for \( x=3 \) Your answer is \( f(3)=\square \)

268. Решите уравнение: \( \begin{array}{l}\text { а) }(y+2)\left(y^{2}-2 y+4\right)-y(y-3)(y+3)=44 \text {; } \\ \text { б) }(m-3)\left(m^{2}+3 m+9\right)-m(m+2)(m-2)=13 \text {; } \\ \text { (B) }(3 a+1)\left(9 a^{2}-3 a+1\right)-3 a\left(9 a^{2}+4\right)=25 \text {; } \\ \text { (A) }(2 n-1)\left(4 n^{2}+2 n+1\right)-4 n\left(2 n^{2}-5\right)=21 \text {. }\end{array} \)

\( \log _ { 2 } ^ { 2 } x - 15 \log _ { 5 } x - 4 \leq 0 \)

268. Решите уравнение: \( \begin{array}{l}\text { a) }(y+2)\left(y^{2}-2 y+4\right)-y(y-3)(y+3)=44 \text {; } \\ \text { б) }(m-3)\left(m^{2}+3 m+9\right)-m(m+2)(m-2)=13 \\ \text { (B) }(3 a+1)\left(9 a^{2}-3 a+1\right)-3 a\left(9 a^{2}+4\right)=25 \text {; } \\ \text { (A) }(2 n-1)\left(4 n^{2}+2 n+1\right)-4 n\left(2 n^{2}-5\right)=21 \text {. }\end{array} \)