Question

72. |x - 3x5| = 6 + y

|9-y + 6| =21
In the equations above, y<0. Which of the following could be the value of x?​

Answer 1

Explanation:

|x-3x^5|=6+y

y<0

|9-y+6|=21

|15-y|=21

15-y±21

either 15-y=21

-y=6

y=-6

or 15-y=-21

y=36

but y<0

so y=-6

|x-3x^5|=6+y

|x-3x^5|=6-6

|x-3x^5|=0

x-3x^5=0

x(1-3x^4)=0

either x=0

or 1-3x^4=0

or (1-√3 x²)(1+√3x²)=0

1-√3 x²=0

x²=1/√3

x=±√(1/√3)

x²=-1/√3

x=±(1/√3)i