Question

Решите неполное квадратное уравнение: х²-5х=0, -7х²+28=0,-0,8х²-9,2=0 ​

Answer 1

х(х-5)=0

х=0

х-5=0

х=5

2)х2 -4=0

х2=4

Х=4/2

Х=2

х1=+2

х2=-2

3)

Answer 2

$\displaystyle\bf\\1)\\\\x^{2} -5x=0\\\\x(x-5)=0\\\\\left[\begin{array}{ccc}x=0\\x-5=0\end{array}\right\\\\\\\left[\begin{array}{ccc}x_{1} =0\\x_{2} =5\end{array}\right\\\\\\Otvet:0 \ ; \ 5\\\\2)\\\\-7x^{2} +28=0\\\\-7x^{2} =-28\\\\x^{2} =-28:(-7)\\\\x^{2}=4 \\\\x_{1,2} =\pm\sqrt{4} =\pm2\\\\Otvet:-2 \ ; \ 2\\\\3)\\\\-0,8x^{2}-9,2=0\\\\-0,8x^{2} =9,2\\\\x^{2}=9,2:(-0,8)\\\\x^{2} =-11,5$

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