Question

Срочно! алгебра 7 кл

Answer 1

1) 25x2-36y2/10x2+12xy*8xy/24y2-20xy=
= ---(5x-6y)(5x+6y)/2x(5x+6y)*8xy/4y(5x-6y)= 8xy/8xy=-1
2) 9a2-16b2/6a+8b*6a/12b-9a= ---(3a-4b)(3a+4b)/2(3a+4b)*6a2/3(3a-4b)=6a2/6=-a2
3) 4a2-20ab+25b2/5b+46:(2a-5b)2/25b2-16= (2a-5b)2/(5b+4)*(5b+4)(5b-4)/(2a-5b)2= 5b-4

Answer 2

6)
$\frac{9a^2-16b^2}{6a+8b} * \frac{6a^2}{12b-9a} = \frac{(3a-4b)(3a+4b)}{2(3a+4b)} * \frac{6a^2}{-3(3a-4b)} =-a^2$
7) 
$\frac{4a^2-20ab+25b^2}{5b+4} : \frac{(2a-5b)^2}{25b^2-16} = \frac{(2a-5b)^2}{5b+4} * \frac{(5b-4)(5b+4)}{(2a-5b)^2} =5b-4$
14)
$\frac{25x^2-36y^2}{10x^2+12xy} * \frac{8xy}{24y^2-20xy} = \frac{(5x-6y)(5x+6y)}{2x(5x+6x)} * \frac{8xy}{-4y(5x-6y)} =-1$