Question

1) Tìm X biết

4.(X+1)^2+(2X-1)^2 -8.(X-1).(X+1)=11

Answer 1

\(4\left(x+1\right)^2+\left(2x-1\right)^2-8\left(x-1\right)\left(x+1\right)=11\)

\(\Rightarrow\left(4x+4\right)^2+\left(2x-1\right)^2-\left(8x-8\right)\left(x+1\right)=11\)

\(\Rightarrow\left(16x^2+32x+16\right)+\left(4x^2-4x+1\right)-\left(8x^2+8x-8x-8\right)=11\)\(\Rightarrow16x^2+32x+16+4x^2-4x+1-8z^2-8x+8x-8=11\)\(\Rightarrow\left(16x^2+4x^2\right)+\left(32x-4x-8x+8x\right)+\left(16+1-8\right)=11\)\(\Rightarrow20x^2+28x+9=11\)

\(\Rightarrow20x^2+28x=2\)

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