Question

What are the solutions to 9x^4-62x^2-7=0

Answer 1

Answer: x=-√7 x=√7

Explanation:

`9x^4-62x^2-7=0\\`

Let x²=t≥0

Hence,

`\displaystyle\\9t^2-62t-7=0\\\\a=9\ \ \ \ b=-62\ \ \ \ c=-7\\\\D=b^2-4ac\\\\D=(-62)^2-4(9)(-7)\\\\D=3844+252\\\\D=4096\\\\√(D)=64\\\\ t=(-bб√(D) )/(2(a)) \\\\t=(-(-62)б64)/(2(9)) \\\\t=(62б64)/(18) \\\\t=-(1)/(9) \\otin(t\geq 0)\\\\t=7\in\\\\Thus\ x^2=7\\\\x=б√(7)`

Answer 2

Answer: x = i√7/3, - i√7/3, 1, -1

Step-by-step explanation: I so hope this helps you