why ??

n ko chia hết cho n - 1 vì chúng là hai số tự nhiên liên tiếp

sory lớp 8 ko bt

=\(\frac{30x^2y^3}{8x^2y^2}\)

Ta có :

\(\frac{6x^2y^2}{8xy^5}=\frac{3x}{4y^3}\)

\(\frac{x^2-xy}{5xy-5y^2}=\frac{x\left(x-y\right)}{5y\left(x-y\right)}=\frac{x}{5y}\)

Hok tốt !

8dm2 = 800 cm2

8 dm² = 800 cm²

mk chắc chắn 100% là 99m<9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999

Gọi d là ước của 2 số: 3a+7&4a+9

+)3a+7\(⋮\)d

=>4.(3a+7)\(⋮\)d

=>12a+28\(⋮\)d(1)

+)4a+9\(⋮\)d

=>3.(4a+9)\(⋮\)d

=>12a+27\(⋮\)d(2)

Từ (1) và(2) suy ra(12a+28)-(12a+27)\(⋮\)d

                      =>12a+28-12a-27\(⋮\)d

                        =>1\(⋮\)d

                       =>d=1

Vì d=1 nên 3a+7&4a+9 là 2 số ntố cùng nhau

Chúc bn học tốt