k21214
Answered

Westonci.ca is the premier destination for reliable answers to your questions, provided by a community of experts. Connect with a community of experts ready to provide precise solutions to your questions quickly and accurately. Explore comprehensive solutions to your questions from knowledgeable professionals across various fields on our platform.

How do you solve x²-10x+9=0 by completing the square?

Sagot :

[tex]x^2-10x+9=0\\\\\underbrace{x^2-2x\cdot5+5^2}_{(*)}-5^2+9=0\\\\(x-5)^2-25+9=0\\\\(x-5)^2-16=0\ \ \ /+16\\\\(x-5)^2=16\iff x-5=-\sqrt{16}\ \vee\ x-5=\sqrt{16}\\\\x-5=-4\ \vee\ x-5=4\\\\x=-4+5\ \vee\ x=4+5\\\\x=1\ \vee\ x=9[/tex]



[tex](*)\ (a-b)^2=a^2-2ab+b^2[/tex]
[tex]x^2-10x+9=0 \\ \\x^2-2\cdot5x+5^2-5^2+9=0\\ \\(x-5)^2-25+9=0\\ \\(x-5)^2=16\\ \\x-5=4\ \ \vee\ \ x-5=-4\\ \\x=9\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x=1[/tex]