Answer :

[tex]x^2- 40 = 0\ \ \ \Leftrightarrow\ \ \ x^2-(2 \sqrt{10} )^2=0\\\\\ \ \ \Leftrightarrow\ \ \ (x-2 \sqrt{10} )(x+2 \sqrt{10} =0\\\\ \ \ \Leftrightarrow\ \ \ x=2 \sqrt{10} \ \ \ \ \ or\ \ \ \ \ x=-2 \sqrt{10[/tex]

Answer:

Given the quadratic equation: [tex]x^2-40=0[/tex]

Addition property of equality states that you add the same number to both sides of an equation.

Step 1.

[tex]x^2-40=0[/tex]

Add 40 to both sides of an equation:

[tex]x^2-40+40=0+40[/tex]

Simplify:

[tex]x^2=40[/tex]                ......[1]

Step 2.

Take square root both sides in equation [1]; we have

[tex]\sqrt{x^2} =\sqrt{40}[/tex]

Simplify:

[tex]x=\pm \sqrt{40} =\pm 2\sqrt{5}[/tex]

Hence, the roots for the given equation is x = [tex]+2\sqrt{5}[/tex] , [tex]-2\sqrt{5}[/tex] .

Therefore, for solving the quadratic equation the first step is; Adding 40 to both sides of an equation.