SOLUTION: Solve step by step :- 9d^4-490d^2+490=0

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Question 871498: Solve step by step :-
9d^4-490d^2+490=0
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Substitute u=d%5E2
9u%5E2-490u%2B490=0
9%28u%5E2-%28490%2F9%29u%2B%28245%2F9%29%5E2%29%2B490=9%28245%2F9%29%5E2
9%28u-%28245%2F9%29%29%5E2=9%28245%2F9%29%5E2-490
%28u-245%2F9%29%5E2=%28245%2F9%29%5E2-490%2F9
%28u-245%2F9%29%5E2=60025%2F81-4410-81
%28u-245%2F9%29%5E2=55615%2F81
u-245%2F9=0+%2B-+sqrt%2855615%29%2F9
u=245%2F9+%2B-+%287%2F9%29sqrt%281135%29
d%5E2=245%2F9+%2B-+%287%2F9%29sqrt%281135%29
Both values are positive.
d=sqrt%28245%2F9+%2B-+%287%2F9%29sqrt%281135%29%29%29