Transcript 7.6 Solving Radical Equations Obj: to solve equations involving

7.6 Solving Radical Equations
Obj: to solve equations involving radicals
Do Now: what is the inverse operation for
addition?
subtraction?
multiplication?
division?
a power of 2?
a square root?
Ex 1: Solve.
a)
x 3
 x  3
2
2
b) 5  4 y  0
 4 y  5
x 9
4
y 5
 y  5
4
4
y  625
check your solutions!
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Ex 2:
a)
4
3
2 x  8  10
4
3
x  81

x


4
3
3
4

  81


x
 81
3
4
3
4
2x  8  4  6
b)
3 x  243
x   3
3
x  27
check your
solutions!!


2
2 x  8  10 2
2x  8  100
2x  92
x  46
Ex 3:
x  4  2x
x  4
2

 2x 
2
x  4x  4  2x
x 2  8 x  16  2 x
x 2  10 x  16  0
x  8x  2  0
x 8  0
x2  0
x 8
x2
Factor this to solve!
Bust da B is too
long…
let’s try a shortcut
HW:
continued…
Obj: to solve equations involving radicals
Do Now: check the solutions from yesterday’s Ex 3
from Ex 3:
x 8
x2
check your
solutions!!
8  4  28
2  4  2 2
4  16
2  4
2 2
44
So, why didn’t one of the
solutions work?
• The solution that did not work is called
an extraneous solution.
• An extraneous solution is a false
solution.
• This is the reason why you MUST
check all solutions!!
Ex 4:
a) 12  2 x  2 x  0
4 x  28  3 2 x  0
b)
12  2 x  2 x
4 x  28  3 2 x
 12  2 x   2 x 
2
2
12  2x  4x

4 x  28
  3
2
2x
4x  28  9  2x
4x  28  18x
12  6x
2 x
28  14x
2 x
Don’t forget to
check your
solutions!!

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