Question

giúp mk nha khẩn cấp

Answer 1

9) \(3x^2+5x-8=0\)

\(\left(3x^2+8x\right)-\left(3x+8\right)=0\)

\(x\left(3x+8\right)-\left(3x+8\right)=0\)

\(\left(x-1\right)\left(3x+8\right)=0\)

\(\Rightarrow x-1=0\) hoặc \(3x+8=0\)

\(x=1\) hoặc \(x=-\dfrac{8}{3}\)

11) \(-5x^2+3x+2=0\)

\(-\left(5x^2-5x\right)-\left(2x-2\right)=0\)

\(-5x\left(x-1\right)-2\left(x-1\right)=0\)

\(\left(-5x-2\right)\left(x-1\right)=0\)

\(\Rightarrow-5x-2=0\) hoặc \(x-1=0\)

\(x=-\dfrac{2}{5}\) hoặc \(x=1\)

13) \(2x\left(3x-5\right)=10-6x\)

\(2x\left(3x-5\right)+\left(6x-10\right)=0\)

\(2x\left(3x-5\right)+2\left(3x-5\right)=0\)

\(\left(2x+2\right)\left(3x-5\right)=0\)

\(\Rightarrow2x+2=0\) hoặc \(3x-5=0\)

\(x=-1\) hoặc \(x=\dfrac{5}{3}\)

2) \(2x^2-2x=\left(x-1\right)^2\)

\(2x^2-2x=x^2-2x+1\)

\(x^2=1\)

\(\Rightarrow x=1\) hoặc \(x=-1\)

4) \(x^2-4=2\left(x-2\right)^2\)

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

\(\left(x-2\right)\left[\left(x+2\right)-2\left(x-2\right)\right]=0\)

\(\Rightarrow x-2=0\) hoặc \(\left(x+2\right)-2\left(x-2\right)=0\)

\(x=2\) hoặc \(-x+6=0\)

\(x=2\) hoặc \(x=6\)