SOLUTION: Please help me with these questions. I don't understand them that well. 2x= {{{ sqrt (4x^2-8x-9) }}} 3x= {{{ sqrt (8x^2+9) }}} {{{ sqrt (-5x)}}} = {{{ sqrt (x+4)}}}

Algebra ->  Radicals -> SOLUTION: Please help me with these questions. I don't understand them that well. 2x= {{{ sqrt (4x^2-8x-9) }}} 3x= {{{ sqrt (8x^2+9) }}} {{{ sqrt (-5x)}}} = {{{ sqrt (x+4)}}}       Log On


   

Question 964131: Please help me with these questions. I don't understand them that well.
2x= +sqrt+%284x%5E2-8x-9%29+
3x= +sqrt+%288x%5E2%2B9%29+
+sqrt+%28-5x%29 = +sqrt+%28x%2B4%29

Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
.
2x=sqrt%284x%5E2-8x-9%29 Square both sides
4x%5E2=4x%5E2-8x-9 Subtract 4x%5E2 from each side.
0=-8x-9 Add 8x to each side.
8x=-9 Divide each side by 8
x=-9%2F8
.
CHECK:
2%28-9%2F8%29=sqrt%284%28-9%2F8%29%5E2-8%28-9%2F8%29-9%29
-18%2F8=sqrt%284%2881%2F64%29%2B9-9%29
-18%2F8=sqrt%28324%2F64%29
-18%2F8=+-%2818%2F8%29
.
.
3x=sqrt%288x%5E2%2B9%29 Square both sides.
9x%5E2=8x%5E2%2B9 Subtract 8x%5E2 from each side.
x%5E2=9 Find the square root of each side.
x=3
.
CHECK:
3x=sqrt%288x%5E2%2B9%29
3%283%29=sqrt%288%283%5E2%29%2B9%29
9=sqrt%2872%2B9%29
9=sqrt%2881%29
9=+-9
.
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sqrt%28-5x%29=sqrt%28x%2B4%29 Square both sides.
-5x=x%2B4 Subtract x from each side.
-6x=4 Divide each side by -6.
x=-4%2F6=-2%2F3
.
CHECK:
sqrt%28-5x%29=sqrt%28x%2B4%29
sqrt%28-5%28-2%2F3%29%29=sqrt%28%28-2%2F3%29%2B4%29
sqrt%2810%2F3%29=sqrt%28%28-2%2F3%29%2B12%2F3%29
sqrt%2810%2F3%29=sqrt%2810%2F3%29