Question

Solve 7x²-30x - 25 = 0 by completing square method

Answer 1

7x²-30x-25=0
divide both sides by 7
x²-30/7x-25/7=0
now,
x²-30/7x+(30/14)²-(30/14)²=25/7
(x-30/14)²=25/7+900/196
(x-30/14)²=700+900/196
(x-30/7)²=1600/196
x-30/7=√1600/196
x-30/7=±40/14
x=40/14+30/7
x=40+60/14
x=100/14
and,
x-30/7=-40/14
x=-40/14+30/7
x=-40+60/14
x=20/14

hope this answer will help you.

Answer 2

$7{x}^{2} - 30x = 25$
$\frac{ {7x}^{2} }{7} - \frac{30x}{7} = \frac{25}{7}$
${x}^{2} - \frac{30x}{7} = \frac{25}{7}$
multiply 30/7 with 1/2 and add its square on both the sides :-
${x}^{2} - \frac{30}{7} + ( \frac{15}{7} ) ^{2} = ( \frac{25}{7}) + ( \frac{15}{7} )^{2}$

now using identity:-
$({x - \frac{15}{2} )}^{2} = \frac{25}{7} + \frac{225}{49}$
$( {x - \frac{15}{7} )}^{2} = \frac{175 + 225}{49}$
$( {x - \frac{15}{7})}^{2} = \frac{400}{49}$
$x - \frac{15}{7} = \sqrt{ \frac{400}{49} }$
$x - \frac{15}{7} = \frac{20}{7}$
$x = \frac{20}{7} + \frac{15}{7}$
$x = \frac{20 + 15}{7}$
$x = \frac{35}{7}$
$x = 5$
Therefore, the value of x by method of completing square is 5.


Hope it will help you.
Mark brainlist if it.