Đặt \(A\left(x\right)=0\)

\(\rightarrow7x^3-5x^2-7x+3-7x^3+5x^2+17x+27=0\)

\(\Leftrightarrow10x+30=0\)

\(\Leftrightarrow10x=-30\)

\(\Leftrightarrow x=-3\)

Vậy \(x=-3\) là nghiệm của đa thức \(A\left(x\right)\)

`A(x)=7x^3-5x^2-7x+3-7x^3+5x^2+17x+27`

`A(x)=(7x^3-7x^3)-(5x^2-5x^2)+(-7x+17x)+(3+27)`

`A(x)=10x+30`

Cho `A(x)=0`

`=>10x+30=0`

`=>10x=-30`

`=>x=-3`

Vậy nghiệm của đa thức `A(x)` là `x=-3`

Chọn B

Ta có: B(x) = 6x4 - 7x3 + 6x2- 7x3 + 4x4 + 3 - 5x + 2x

= 10x4 - 14x3 + 6x2 - 3x + 3.

54/35

\(-\frac{23}{7}.\frac{3}{10}+\frac{13}{7}.\frac{3}{10}\)

\(=\frac{3}{10}.\left(\left(-\frac{23}{7}\right)+\frac{13}{7}\right)\)

\(=\frac{3}{10}.\left(\frac{-10}{7}\right)\)

\(=\frac{-3}{7}\)

=7x(3+3+2+1)

=7x9

=63

7x3+7x2+7x3+7

= 7x (3+2+3+7)

= 7x 15

= 105

3/7x3/13+3/7:13/10+6/14

=3/7x3/13+3/7x10/13+6/14

=3/7x(3/13+10/13)+6/14

=3/7x1+6/14

=3/7+6/14

=3/7+3/7

=6/7

Đề:...........

= 3/7 x 3/13 + 3/7 x 10/13 + 3/7

= 3/7 x (3/13 + 10/13 + 1)

= 3/7 x ( 1 + 1 )

= 3/7 x 2

= 6/7

\(\left(x+3\right)\left(x^2-3x+9\right)=7x^3+21x\\ \Leftrightarrow x^3+27=7x^3+21x\\ \Leftrightarrow6x^3+21x-27=0\\ \Leftrightarrow\left(6x^3-6x^2\right)+\left(6x^2-6x\right)+\left(27x-27\right)=0\\ \Leftrightarrow\left(x-1\right)\left(6x^2+6x+27\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x-1=0\\6x^2+6x+27=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=1\\6\left(x^2+x+\dfrac{1}{4}\right)+\dfrac{51}{2}=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=1\\6\left(x+\dfrac{1}{2}\right)^2+\dfrac{51}{2}=0\left(vô.lí\right)\end{matrix}\right.\)

Vậy \(x=1\)

\(\Leftrightarrow x^3+27-7x^3-21x=0\)

\(\Leftrightarrow-6x^3-21x+27=0\)

\(\Leftrightarrow-6x^3+6x-27x+27=0\)

\(\Leftrightarrow-6x\left(x-1\right)\left(x+1\right)-27\left(x-1\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(6x^2+6x+27\right)=0\)

hay x=1

107 - {38 - [7 x 3² - 24 : 6 + (9 - 7)³]} : 15

= 107 - {38 - [7 x 9 - 4 + 2³]} : 15

= 107 - {38 - [63 - 4 + 8]} : 15

= 107 - {38 - [59 + 8]} : 15

= 107 - (38 - 67) : 15

= 107 - (-29) : 15

= 107 - (-1,99)

= 107 + 1,99

= 108,99

107-{38+[7.3^2-24:6+(9-7)^3]}:15

=107-{38+[7.9-24:6+23]} :15

=107-{38+[63-4+8]}:15

=107-{38+67}:15

=107-105:15

=107-7=7

dễ lắm

3/7\(\times\)(2/5+3/5+1)

=3/7 nhân 2

=6/7