Question

1)x^4-5x^2-6=0
2)4x^4-5x^2+1=0
3)x^4-9x^2+20=0
4)16y^4+145y^2+9=0
5)12y4-7y^2+1=0

Answer 1

1) x⁴-5x²-6=0

t²-5t-6=0

t= -1

t=6

x²= -1

x²=6

x€/R

x= -√6

x=√6

x1= -6, x2=√6.

2)4x⁴-5x²+1=0

4t²-5t+1=0

t=1/4

t=1

x²=1/4

x²=1

x= -1/2

x=1/2

x= -1

x=1

x1= -1, x2= -1/2, x3=1/2, x4=1.

3) x⁴-9x+20=0

t²-9t+20=0

t=4

t=5

x²=4

x²=5

x= -2

x=2

x= -√5

x=√5

x1= -√5, x2= -2, x3=2, x4=√5.

4)16y⁴+145y²+9=0

y= €/R.

5) 12y4-7y²+1=0

48y-7y²+1=0

-7y²+48y+1=0

7y²-48y-1=0

y= -(-48)±√(-48)²-4×7×(-1)/2×7

y=48±√2304+28/14

y=48±2332/14

y=48+2√583/14

y=48-2√583/14

y=24+√583/7

y=24-√583/7

y1=24-√583/7, x2=24+√583/7.