Question #de83c

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Answer 1 · 2017-11-02T13:23:57

$x=5$ or $x=(-5)/2$

$2x^2-25-5x=0$
$2x^2-5x-25=0$
$2x^2-10x+5x-25=0$
$2x(x-5)+5(x-5)=0$
$(2x+5)(x-5)=0$
$(2x+5)=0$ or $x-5=0$
$2x=-5$ or $x=5$
$x=(-5)/2$ or $x=5$

Answer 2 · 2017-11-02T14:12:56

$x=5,-5/2$

The quadratic formula is $x=(-b+-sqrt(b^2-4ac))/(2a)$

Given equation is $2x^2-5x-25$

Here $a=2$ , $b=-5$ and $c=-25$

Put these values in the quadratic formula.

$x=(-(-5)+-sqrt((-5)^2-4 xx (2) xx (-25)))/(2 xx 2)$

$x=(5+-sqrt(25+200))/4$

$x=(5+-15)/4$

So $x=(5+15)/4$ or $x=(5-15)/4$

$x=20/4$ or $x=(-10)/4$

$x=5$ or $x=(-5)/2$