2 x 3 = 6

mk k rùi

2 x 3 = 6 

OK

\(a.\dfrac{6}{7}-\dfrac{4}{21}=\dfrac{18-4}{21}=\dfrac{14}{21}=\dfrac{2}{3}\\ b.6\times\dfrac{12}{18}=\dfrac{6\times12}{18}=\dfrac{4}{1}=4\\ c.\dfrac{2}{5}\times\dfrac{3}{7}+\dfrac{2}{5}\times\dfrac{4}{7}-\left(\dfrac{3}{7}+\dfrac{4}{7}\right)\times\dfrac{2}{5}=\dfrac{7}{7}\times\dfrac{2}{5}=1\times\dfrac{2}{5}=\dfrac{2}{5}\)

18/21 - 4/21 = 14/21 = 2/3

(3/7+4/7)x 2/5= 7/7x 2/5 = 1x2/5 = 2/5

Gọi \(A=\left(x-1\right)\left(x+3\right)\left(x+2\right)\left(x+6\right)\)

\(=\left(x-1\right)\left(x+6\right)\left(x+3\right)\left(x+2\right)\)

\(=\left(x^2+5x-6\right)\left(x^2+5x+6\right)\)

\(=\left(x^2+5x\right)^2-6^2\)

\(=\left[x\left(x+5\right)\right]^2-36\ge-36\) Có GTNN là - 36

Dấu "=" xảy ra \(\Leftrightarrow\left[x\left(x+5\right)\right]^2=0\Rightarrow\orbr{\begin{cases}x=0\\x=-5\end{cases}}\)

Vậy GTNN của A là - 36 tại \(\orbr{\begin{cases}x=0\\x=-5\end{cases}}\)

GTNN là 0

Đặt A = 5 × 6 + 6 × 7 + 7 × 8 + ... + 99 × 100

3A = 5 × 6 × (7 - 4) + 6 × 7 × (8 - 5) + 7 × 8 × (9 - 6) + ... + 99 × 100 × (101 - 98)

3A = 5 × 6 × 7 - 4 × 5 × 6 + 6 × 7 × 8 + 7 × 8 × 9 - 6 × 7 × 8 + .... + 99 × 100 × 101 - 98 × 99 × 100

3A = 99 × 100 × 101 - 4 × 5 × 6

3A = 3 x (33 × 100 × 101 - 4 × 5 × 2)

A = 33 × 100 × 101 - 4 × 5 × 2

A = 333300 - 40

A = 333260

333260

9X9X9

=81X9

=729

5x5x5x5

=25x5x5

=125x5

=625

5 x 5 x 5 x 5 = 25 x 25 = 625

k cho tui

x = 10 ( bớt 2 vế đi 60 )

60+10=60+x

70=60+x

70-60=x

x=10

Vậy x=10

60 x 2 = 120 nha bạn

Bạn trả lời đi để mình tk cho . Nhớ tk mình đấy

60 x 2 = 120 

Đung 1000 %

Bằng 1000

=10000