-48+48.(-78)+48.(-21)

=48.(-1)+48.(-78)+48.(-21)

=48.(-1+(-78)+(-21))

=48.(-100)

=-4800

-48+48x(-78)+48x(-21)=-4800

-48 + 48 x ( -78 ) + 48 x ( -21 ) 

= -48 + 48 x [ (-78 ) + (-21 ) ]

= -48 + 48 x -99

= -48 + -4752

= -4800

\(48\left(x-2\right)=48x+25\)

\(\Rightarrow48x-48.2=48x+25\)

\(\Rightarrow48x-96=48x+25\)

\(\Rightarrow48x-48x=25+96=121\)

\(\Rightarrow0=121\)

=> Vô lí

   48 - 48 x ( 246 + 54 - 300 )

= 48 - 48 x ( 300 - 300 )

= 48 - 48 x 0

= 48 - 0

= 48

Tk Mình Nha ( MK CHUẨN BỊ LÊN LỚP 6 THUI )

\(48-48.\left(246+54-300\right)\)

\(=48-48\left(300-300\right)\)

\(=48-48.0\)

\(=48-0\)

\(=48\)

48-48×(246+54-300)

=48-48×(300-300)

=48-48×0

=48×1-48×0

=48×(1-0)

=48×1

=48

\(\dfrac{31}{48}\times\dfrac{32}{93}\)

\(=\dfrac{31\times32}{48\times93}\)

\(=\dfrac{1\times2}{3\times3}\)

\(=\dfrac{2}{9}\)

============

\(\dfrac{77}{80}\times\dfrac{48}{49}\)

\(=\dfrac{77\times48}{80\times49}\)

\(=\dfrac{11\times3}{5\times7}\)

\(=\dfrac{33}{35}\)

=============

\(\dfrac{154}{125}\times\dfrac{25}{44}\)

\(=\dfrac{154}{125}\times\dfrac{25}{44}\)

\(=\dfrac{7\times1}{5\times2}\)

\(=\dfrac{7}{10}\)

x⁴+4x³-4x²-48x-48=0

=> x⁴+4(x³-x²) - 48x = 48

=> x⁴ + 4[x²(x-1)] - 48x = 48 

     \(x^4+4x^3-4x^2-48x-48=0\)

\(\Leftrightarrow\)\(x^4-2x^3-4x^2+6x^3-12x^2-24x+12x^2-24x-48=0\)

\(\Leftrightarrow\)\(x^2\left(x^2-2x-4\right)+6x\left(x^2-2x-4\right)+12\left(x^2-2x-4\right)=0\)

\(\Leftrightarrow\)\(\left(x^2-2x-4\right)\left(x^2+6x+12\right)\)

\(\Leftrightarrow\)\(\left[\left(x-1\right)^2-5\right]\left(x^2+6x+12\right)=0\)

\(\Leftrightarrow\)\(\left(x-1-\sqrt{5}\right)\left(x-1+\sqrt{5}\right)\left(x^2+6x+12\right)=0\)

Ta có:   \(x^2+6x+12=\left(x+3\right)^2+3>0\)

\(\Rightarrow\)\(\orbr{\begin{cases}x-1-\sqrt{5}=0\\x-1+\sqrt{5}=0\end{cases}}\)      

\(\Leftrightarrow\)\(\orbr{\begin{cases}x=1+\sqrt{5}\\x=1-\sqrt{5}\end{cases}}\)

Vậy...

\(\Leftrightarrow\dfrac{3x-1}{\left(6x-7\right)\left(3x+4\right)}-\dfrac{4x}{\left(8x-3\right)\left(3x+4\right)}=\dfrac{3}{\left(8x-3\right)\left(6x-7\right)}\)

=>(3x-1)(8x-3)-4x(6x-7)=3(3x+4)

=>24x^2-9x-8x+3-24x^2+28x=9x+12

=>11x+3=9x+12

=>2x=9

=>x=9/2

\(48x:\frac{21}{4}=7.5:\frac{25}{8}\)
\(48x:\frac{21}{4}=\frac{12}{5}\)

\(48x=\frac{12}{5}\cdot\frac{21}{4}\)

\(48x=\frac{63}{5}\)

\(x=\frac{63}{5}:48\)

\(x=\frac{21}{80}\)

\(3x^3-48x=0\)

\(3x\cdot\left(x^2-16\right)=0\)

\(\Rightarrow\orbr{\begin{cases}3x=0\\x^2-16=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x=\left\{\pm4\right\}\end{cases}}\)

Vậy,............

Đáp án là c)100 nhé!

Mình nhanh nhất

Học tốt!

a )100

99 x 48 = 48 x 100 - 48

=> Đáp án c) 100