<p>If x^2 - y^2 = 77 and x + y = 11. What is the value of x?</p>
<p>NVM, I just figured it out.
Wow. It was so easy...Took me long enough.</p>
<p>You're all welcomed to try it.</p>
<p>For some problems, plugging in possible answer choices is even quicker than solving the problem the algebraic way. (If there is an algebraic way)</p>
<p>Our system is:
x^2 - y^2 =77
x + y =11</p>
<p>Since we want to find the value of x, we need to isolate the y on one equation. The second equation is easier.</p>
<p>So we have X + y =11. Subtracting x from both sides, we get y =11-x.
Substituting that into the first equation, we have x^2 - (11-x)^2 = 77.</p>
<p>Distributing the (11-x)^2, our new equation is x^2 - x^2 +22x - 121 =77.
Simplifying, we get 22x-121=77. Adding 121 to both sides, we get 22x=198.
Dividing by 22, we get x=9, which is our desired result.</p>
<p>yeah, 9.
Thats what the book says.</p>
<p>It’s only a medium question but it took me so long to figure it out -.-</p>
<p>If x^2 - y^2 = 77 and x + y = 11. What is the value of x?</p>
<p>x^2-y^2=(x+y)(x-y)
Since (x+y)=11
X^2-y^2=(11)(x-y)=77
Divide both sides by 11
(x-y)=7</p>
<p>x-y=7
x+y=11</p>
<p>System of Equations. Add these up and you’ll get 2x=18 (note -y + y cancels out). Divide both sides by 2 and you get x=9. Plug it in:</p>
<p>X=9
Y=2</p>
<p>You could plug these variables back into the original (9^2=81-(y^2(4))=77)</p>
<p>If you have trouble solving systems of equations: </p>
<p>[Solve</a> Systems of Equations - Tutorial](<a href=“http://www.analyzemath.com/Tutorial-System-Equations/Tutorial-System-Equations.html]Solve”>Page Moved)</p>
<p>uhh… i tried doing this whole complicated thing when i could have just factored x^2-y^2. That’s summer vacation for you!</p>