Question

find the solution of x2-4x-8=0

Answer 1

Answer:

$x = (2 + 2\sqrt{3} ) \: or \: (2 - 2\sqrt{3} )$

Step-by-step explanation:

${x}^{2} - 4x - 8 = 0 \\ a = 1 \\ b = - 4 \\ c = - 8 \\ using \: quadratic \: formula - \\ = ( - b + - \sqrt{(b {}^{2} - 4 ac)}) \div2a \\ putting \: the \: value \: of \: a \: b \: and \: c \\ = (4 + - \sqrt{(16 + 32)}) \div 2 \\ =(4 + - \sqrt{48} ) \div 2 \\ = (4 + - 4 \sqrt{3} ) \div 2 \\ = 2(2 + - 2 \sqrt{3 }) \div 2 \\ = 2 + - 2 \sqrt{3} \\ therefore\: \: value \: of \: x \: is \: (2 + 2 \sqrt{3} )(2 - 2 \sqrt{3} )$

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