Question

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

Answer 1

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$\red{\bold{\underline{\underline{Solution:}}}}$

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

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Answer 2

Solution:

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