7 x 5 + 6X + 25 = 812

35 + 6X + 25 = 812

6X = 812 - 35 - 25

6X = 752

X = 752 : 6

X = 376/3

\(\frac{2x^4+6x^3+18x^2}{x^4-27x}=\frac{2x^2.\left(x^2+3x+9\right)}{x.\left(x^3-27\right)}\)

\(=\frac{2x^2.\left(x^2+3x+9\right)}{x.\left(x-3\right)\left(x^2+3x+9\right)}=\frac{2x}{x-3}\)

\(\Leftrightarrow sin8x-\sqrt{2}cos8x=cos6x-\sqrt{2}sin6x\)

\(\Leftrightarrow\dfrac{1}{\sqrt{3}}sin8x-\dfrac{\sqrt{2}}{\sqrt{3}}cos8x=\dfrac{1}{\sqrt{3}}cos6x-\dfrac{\sqrt{2}}{\sqrt{3}}sin6x\)

Đặt \(\dfrac{1}{\sqrt{3}}=cosa\) với \(a\in\left(0;\dfrac{\pi}{2}\right)\Rightarrow\dfrac{\sqrt{2}}{\sqrt{3}}=sina\)

\(\Rightarrow sin8x.cosa-cos8x.sina=cos6x.cosa-sin6x.sina\)

\(\Leftrightarrow sin\left(8x-a\right)=cos\left(6x+a\right)\)

\(\Leftrightarrow sin\left(8x-a\right)=sin\left(\dfrac{\pi}{2}-6x-a\right)\)

\(\Leftrightarrow...\)

3/25 x ( 15/7 - 2/7 ) + 3/7 x 1/25 

= 3/25 x 13/7 + 3/7 x 1/25 

= (3 x 13/7 + 3/7 ) x 1/25 

= 42/7 x 1/25 

= 6 x 1/25 

= 6/25

\(\dfrac{3}{25}\times\dfrac{15}{7}+\dfrac{3}{7}\times\dfrac{1}{25}-\dfrac{2}{7}\times\dfrac{3}{25}\)

\(=\dfrac{3}{25}\times\left(\dfrac{15}{7}-\dfrac{2}{7}\right)+\dfrac{3}{7}\times\dfrac{1}{25}\)

\(=\dfrac{3}{25}\times\dfrac{13}{7}+\dfrac{3}{7}\times\dfrac{1}{25}\)

\(=\dfrac{3\times13}{25\times7}+\dfrac{3\times1}{7\times25}\)

\(=\dfrac{39}{175}+\dfrac{3}{175}\)

\(=\dfrac{39+3}{175}\)

\(=\dfrac{42}{175}\)

\(=\dfrac{6}{25}\)

A = \(\dfrac{3}{25}\) \(\times\) \(\dfrac{15}{7}\) + \(\dfrac{3}{25}\) \(\times\) \(\dfrac{1}{7}\) - \(\dfrac{2}{7}\times\) \(\dfrac{3}{25}\)

A = \(\dfrac{3}{25}\) \(\times\)( \(\dfrac{15}{7}\) + \(\dfrac{1}{7}-\dfrac{2}{7}\))

A = \(\dfrac{3}{25}\) \(\times\) \(\dfrac{14}{7}\)

A = \(\dfrac{6}{25}\)

=>\(\dfrac{3x+5}{3}>\dfrac{-4}{6x+5}\)

=>\(\dfrac{18x^2+15x+30x+25+12}{3\left(6x+5\right)}>0\)

=>\(\dfrac{18x^2+45x+37}{3\left(6x+5\right)}>0\)

=>6x+5>0

=>x>-5/6

=2(2x^3-3x^2+3x-1)

=2(2x^3-x^2-2x^2+x+2x-1)

=2(2x-1)(x^2-x+1)

4 kg = 0,4 yến .

cảm ơn ạ

TL

4kg = 4 yến

Nhớ k cho mình nha

\(143-43\times\left[\left(25:5^2\right)-5^2\right]=143-43\times\left(1-5^2\right)=143-43\times\left(-24\right)=143+1032=1175\)

143 -43 x [(25 : 5²) - 5² ]

= 100 x [( 25 : 25 ) - 25 ]

= 100 x [ 1 - 25 ]

= 100 x - 24

= -2400

Đề bài có sai ở đâu k z ?

ta có :

\(8x\left(3x-8\right)+6x\left(-4x+7\right)=-88\)

\(\Leftrightarrow24x^2-64x-24x^2+42x=-88\Leftrightarrow-22x=-88\Leftrightarrow x=4\)

`8x (3x-8) +6x (-4x+7)=-88`

`-> 24x^2 - 64x - 24x^2 + 42x=-88`

`-> (24x^2 - 24x^2)+(-64x+42x)=-88`

`-> -22x=-88`

`->x=-88 : (-22)`

`->x=4`

Vậy `x=4`