3:

a: -5x-16=-46

=>-5x=-46+16=-30

=>5x=30

=>\(x=\dfrac{30}{5}=6\)

b: -80-(-16-x)=20

=>\(-x-16=-80-20=-100\)

=>x+16=100

=>x=100-16=84

2:

a: \(\left(45-3456\right)+3456\)

\(=45+3456-3456\)

=45

b: \(\left(77+22-75\right)-\left(-25-78-13\right)\)

\(=77+13+22+78-75+25\)

\(=90+100-50\)

=140

c: \(-25\cdot63-25\cdot37\)

\(=-25\left(63+37\right)\)

\(=-25\cdot100=-2500\)

mn = 678 x 3456 = 2374272

độ dài cạnh MN là : 

678 + 3456 = 4134 

Đáp số : 4134

tick di

ket qua la 678 *3456=2343168

678 x 91 - 678 xa = 678

678 x ( 91-a ) =678

           91 -a  = 6780:678

           91-a   = 10

              a     = 91-10

              a     = 81

vậy a=81

678*91 -678*a = 6780 thi a = 81 vi 91-81= 10 ma 10*678 =6780 vay thoai man dau bai

=678.[91-a]=6780

91-a=6780:678

91-a=10

a=91-10

a=81

x + 3456 = 5478

            x = 5478 - 3456

            x = 2022

tk nhe Haruko

\(X=5478-3456=2022\)

\(x+3456=5478\)

\(x=5478-3456\\ x=2022\)

Ta có: \(\left(x-\dfrac{1}{5}\right)^{2004}\ge0\forall x\)

\(\left(y+\dfrac{2}{5}\right)^{100}\ge0\forall y\)

\(\left(z-3\right)^{678}\ge0\forall z\)

Do đó: \(\left(x-\dfrac{1}{5}\right)^{2004}+\left(y+\dfrac{2}{5}\right)^{100}+\left(z-3\right)^{678}\ge0\forall x,y,z\)

Dấu '=' xảy ra khi \(\left(x,y,z\right)=\left(\dfrac{1}{5};\dfrac{-2}{5};3\right)\)

Vì \(\left(x-\dfrac{1}{5}\right)^{2004}\ge0,\left(y+0,4\right)^{100}\ge0,\left(z-3\right)^{678}\ge0\)

\(\Rightarrow\left(x-\dfrac{1}{5}\right)^{2004}+\left(y+0,4\right)^{100}+\left(z-3\right)^{678}\ge0\)

Dấu "=" xảy ra \(\Leftrightarrow\left\{{}\begin{matrix}x-\dfrac{1}{5}=0\\y+0,4=0\\z-3=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{1}{5}\\y=-0,4\\z=3\end{matrix}\right.\)

Vậy \(\left(x,y,z\right)=\left(\dfrac{1}{5};-0,4;3\right)\)

Vì \(\left(x-\dfrac{1}{5}\right)^{2004}\ge0\forall x\)

\(\left(y+0,4\right)^{100}\ge\forall y\)

\(\left(z-3\right)^{678}\ge0\forall z\)

\(\Rightarrow\left(x-\dfrac{1}{5}\right)^{2004}+\left(y+0,4\right)^{100}+\left(z-3\right)^{678}\ge0\)

mà \(\left(x-\dfrac{1}{5}\right)^{2004}+\left(y+0,4\right)^{100}+\left(z-3\right)^{678}=0\)

Dấu ''='' xảy ra khi \(x=\dfrac{1}{5};y=-0,4;z=3\)

3366 nha bạn

x=-3435 đó bạn

ngu nhu cho the may,bai nay de vn