Question

Solve for x and give the answer correct to 2 decimal places $2x^2-10x+5=0$

• A. 7:4
• B. $x=-4.44,or-0.56$
• C. $x=-4.44,or0.56$
• D. $x=4.44,or-0.56$

Answer 1

The correct option is A

7:4

Given: $2x^2-10x+5=0$

$\Rightarrow a=2,b=-10,c=5$

$b^2-4ac=(-10{)}^2-4(2\left)\right(5)$

= $100-40=60$

$\Rightarrow \sqrt{b^2-4ac}=\sqrt{60}$

= $7.746$

$x=\frac{x\pm \sqrt{b^2-4ac}}{2a}$

$\Rightarrow x=\frac{10+7.746}{4},or\frac{10-7.746}{4}$

$\Rightarrow x=\frac{17.746}{4},or\frac{2.254}{4}$

$\Rightarrow x=\frac{17.746}{4},or\frac{2.254}{4}$

$\Rightarrow x=4.44,or0.56$