\(x^2+3x+m-1=0\left(1\right)\)

Thay \(m=3\) vào \(\left(1\right)\)

\(\Rightarrow x^2+3x+3-1=0\)

\(\Rightarrow x^2+3x+2=0\)

\(\Rightarrow x^2+x+2x+2=0\)

\(\Rightarrow x\left(x+1\right)+2\left(x+1\right)=0\)

\(\Rightarrow\left(x+2\right)\left(x+1\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x+2=0\\x+1=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=-2\\x=-1\end{matrix}\right.\)

Vậy \(S=\left\{-2;-1\right\}\) khi \(m=3\)

câu a) dễ rồi ai chả bt làm, Mik cần câu b)

(\(x\) + 1/4 - 1/3) : (2 x 7\(\frac16\) - 1/4) = 7/46

(\(x+\frac14\) - 1/3) : (2 x \(\frac{43}{6}\) - 1/4) = 7/46

(\(x\) + 1/4 - 1/3) : (43/3 - 1/4) = 7/46

(\(x\) + 1/4 - 1/3) : (172/12 - 3/12) = 7/46

(\(x\) + 1/4 - 1/3) : 169/12 = 7/46

\(x\) + 1/4 - 1/3 = 7/46 x 169/12

\(x\) + 1/4 - 1/3 = 1183/552

\(x\) + 1/4 = 1183/552 + 1/3

\(x\) + 1/4 = 1367/552

\(x\) = 1367/552 - 1/4

\(x\) = 1229/552

7,x²-2xy+y²+3x-3y=(x-y)²+3(x-y)=(x-y)(x-y+3)

8,x⁴+4=(x⁴+4x²+4)-4x²=(x²+2)²-(2x)²=(x²-2x+2)(x²+2x+2)

9,4x(x+1)²-5x²(x+1)-4.(x+1)=(x+1)\(\left[4x\left(x+1\right)-5x^2-4\right]\)=(x+1)(4x²+4x-5x²-4)=(x+1)(-x²+4x-4)=-(x+1)(x-2)²

( x + 1/3 - 1/4 ) : ( 2 + 1/6 - 1/4 ) = 7/46

( x + 1/3 - 1/4 ) : ( 13/6 - 1/4 ) = 7/46

( x + 1/3 - 1/4 ) : 23/12 = 7/46

x + 1/3 - 1/4 = 7/46 x 23/12

x + 1/3 - 1/4 = 7/24

x + 1/3 = 7/24 + 1/4

x + 1/3 = 13/24

        x = 13/24 - 1/3

        x = 5/24

(x + 1/12) : 23/12 = 7/46

(x+1/12) = 7/46 . 23/12

x + 1/12 = 7/24

x = 7/24 - 1/12

x = 5/24

x=3/8