Odpowiedź:
[tex]a)\\\\(x-3)(x+5)=0\\\\x-3=0\ \ \ \ \vee\ \ \ \ x+5=0\\\\x=3\ \ \ \ \ \ \ \ \vee\ \ \ \ x=-5\\\\\\b)\\\\5x(x-\sqrt{7})=0\ \ /:5\\\\x(x-\sqrt{7})=0\\\\x=0\ \ \ \ \vee\ \ \ \ x-\sqrt{7}=0\\\\x=0\ \ \ \ \vee\ \ \ \ x=\sqrt{7}\\\\\\c)\\\\x^2+8x+7=0\\\\x^2+7x+x+7=0\\\\x(x+7)+(x+7)=0\\\\(x+7)(x+1)=0\\\\x+7=0\ \ \ \ \vee\ \ \ \ x+1=0\\\\x=-7\ \ \ \ \ \ \vee\ \ \ \ x=-1 [/tex]
[tex]d)\\\\-x^2+5x+3=0\ \ /\cdot(-1)\\\\x^2-5x-3=0\\\\a=1\ \ ,\ \ b=-5\ \ ,\ \ c=-3\\\\\Delta=b^2-4ac\\\\\Delta=(-5)^2-4\cdot1\cdot(-3)=25+12=37\\\\\sqrt{\Delta}=\sqrt{37}\\\\x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-\sqrt{37}}{2\cdot1}=\frac{5-\sqrt{37}}{2}\\\\x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+\sqrt{37}}{2\cdot1}=\frac{5+\sqrt{37}}{2} [/tex]
