SOLUTION: Find every value for the variable that makes the expression undefined x^2-36 over x^2+11x+28

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Find every value for the variable that makes the expression undefined x^2-36 over x^2+11x+28      Log On


   

Question 1006634: Find every value for the variable that makes the expression undefined
x^2-36 over x^2+11x+28
Found 2 solutions by MathLover1, MathTherapy:
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

%28x%5E2-36%29%2F%28x%5E2%2B11x%2B28%29
A fraction is said to be undefined (or have no meaning) when the denominator+=+0.
%28x%5E2%2B11x%2B28%29=0..........solve for x
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%28-11+%2B-+sqrt%28+11%5E2-4%2A1%2A28+%29%29%2F%282%2A1%29+
x+=+%28-11+%2B-+sqrt%28+121-112+%29%29%2F2+
x+=+%28-11+%2B-+sqrt%28+9+%29%29%2F2+
x+=+%28-11+%2B-+3%29%2F2+
solutions:
x+=+%28-11+%2B+3%29%2F2+
x+=+-8%2F2+
x+=+-4+
or
x+=+%28-11+-+3%29%2F2+
x+=+-14%2F2+
x+=+-7+
the values +-4+ and -7+ for the variable will make the expression undefined


Answer by MathTherapy(10549) About Me  (Show Source):
You can put this solution on YOUR website!

Find every value for the variable that makes the expression undefined
x^2-36 over x^2+11x+28
Set denominator equal to 0

x%5E2+%2B+11x+%2B+28+=+0

(x + 7)(x  + 4) = 0 ------- Factoring trinomial

x = - 7     OR      x = - 4 ------- Solving for x, after setting each factor equal to 0

Expression is undefined when: highlight_green%28system%28x+=+-+7_OR%2Cx+=+-+4%29%29