má có thực hiện phép tính cx hỏi ngu z bé

a)=(6-16).3-24

   =-10.3-24

   =-30-24

   =54

b)=-20+(-7)+19

   =-27+19

   =-8

A, 13400

B,56

Bài 2:

a)\(\dfrac{1}{3}\sqrt{x-2}-\dfrac{2}{3}\sqrt{9x-18}+6\sqrt{\dfrac{x-2}{81}}=-4\) (đk: \(x\ge2\))

\(\Leftrightarrow\dfrac{1}{3}\sqrt{x-2}-\dfrac{2}{3}\sqrt{9\left(x-2\right)}+\dfrac{6}{\sqrt{81}}\sqrt{x-2}=-4\)

\(\Leftrightarrow\dfrac{1}{3}\sqrt{x-2}-2\sqrt{x-2}+\dfrac{2}{3}\sqrt{x-2}=-4\)

\(\Leftrightarrow-\sqrt{x-2}=-4\) \(\Leftrightarrow x-2=16\)

\(\Leftrightarrow x=18\) (thỏa)

Vậy...

b)\(\sqrt{9x^2+12x+4}=4x\)(Đk:\(9x^2+12x+4\ge0\))

\(\Leftrightarrow\left\{{}\begin{matrix}4x\ge0\\9x^2+12x+4=16x^2\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x\ge0\\-7x^2+12x+4=0\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}x\ge0\\-7x^2+14x-2x+4=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x\ge0\\\left(x-2\right)\left(-7x-2\right)=0\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}x\ge0\\\left[{}\begin{matrix}x=2\\x=-\dfrac{2}{7}\end{matrix}\right.\end{matrix}\right.\)

\(\Leftrightarrow x=2\) (tm đk)

Vậy...

c) \(\sqrt{x-2\sqrt{x-1}}=\sqrt{x-1}\) (đk: \(x\ge1\))

\(\Leftrightarrow x-2\sqrt{x-1}=x-1\)

\(\Leftrightarrow\sqrt{x-1}=\dfrac{1}{2}\) \(\Leftrightarrow x=\dfrac{5}{4}\) (tm)

Vậy...

a: =(2căn 3-8căn 3)(căn 3-1)

=-6căn 3*(căn 3-1)

=-18+6căn 3

b: \(=\dfrac{6-2\sqrt{5}}{\sqrt{5}-3}-\sqrt{5}+2\)

=-2-căn 5+2=-căn 5

c: \(=3\sqrt{2a}-3a\sqrt{2a}+2\sqrt{2a}-\dfrac{1}{4}\cdot8\sqrt{2a}\)

=\(3\sqrt{2a}-3a\cdot\sqrt{2a}\)

Bài 1:

a)-54

b)-8

Bài 2:

a)(x-14):5=4¹⁵:4¹³

⇔(x-14):5=4²

⇔(x-14):5=16

⇔x-14=80

⇔x=94

b)7x-15x=15-175

⇔-8x=-160

⇔x=20

mk viết sai 

cộng nhé các bạn

 A  15.133+15.17-15.50               B  48.19+48.115+134.52                   

=15.(133+17-50)                        = 48.(19+115)+134.52

=15.100                                      =48.134+134.52

=1500.                                        =134.(48+52)=134.100=13400

còn câu C,D nữa giúp mk với

a) Ta có: \(\dfrac{2\sqrt{8}-\sqrt{12}}{\sqrt{18}-\sqrt{48}}-\dfrac{\sqrt{5}+\sqrt{27}}{\sqrt{30}+\sqrt{162}}\)

\(=\dfrac{-2\left(\sqrt{3}-\sqrt{8}\right)}{\sqrt{6}\left(\sqrt{3}-\sqrt{6}\right)}-\dfrac{\sqrt{5}+\sqrt{27}}{\sqrt{6}\left(\sqrt{5}+\sqrt{27}\right)}\)

\(=\dfrac{-3}{\sqrt{6}}=\dfrac{-3\sqrt{6}}{6}=\dfrac{-\sqrt{6}}{2}\)

b) Ta có: \(\left(1+\sqrt{2}+\sqrt{3}\right)\left(1-\sqrt{2}-\sqrt{3}\right)\)

\(=1-\left(\sqrt{2}+\sqrt{3}\right)^2\)

\(=1-5-2\sqrt{6}\)

\(=-4-2\sqrt{6}\)

tinh nhanh ha ban??

không  , tính bình thường thôi .

\(47-\left[\left(45.2^4-5^2.12\right):14\right]\)

\(=47-\left[\left(45.16-25.12\right):14\right]\)

\(=47-\left[\left(720-300\right):14\right]\)

\(=47-\left[420:14\right]\)

\(=47-30\)

\(=17\)

a)\(\left(-3\right).8.\left(-2\right).5=\left(-3\right).\left(-2\right).8.5\)

                                          \(=6.40=240\)

b)\(127-18.\left(5+6\right)=127-18.11\)

                                             \(=127-198=-71\)

c)\(125-\left(-75\right)+32-\left(48+32\right)=125+75+32-48-32\)

                                                                              \(\left(125+75\right)+\left(32-32\right)-48=200-48=152\)

d)\(3.\left(-4\right).2+2.\left(-5\right)-20=-12.2+2.\left(-5\right)-20\)

                                                             \(=\left(-12-5\right).2-20=-17.2-20=-140-20=-160\)

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