The Student Room Group

solve for x

solve for x

1>a>3/4 1>a>3/4


x3(x+1)=(x+a)(2x+a) x^3(x+1)=(x+a)(2x+a)




without using a calculator/ wolphram!
Reply 1
Do you want help on it or just as a challenge?
Reply 2
Original post by jit987
Do you want help on it or just as a challenge?


challenge
Reply 3
x4+x32x23axa2=0x^4+x^3-2x^2-3ax-a^2=0

x3+x22x=a2x+3ax^3+x^2-2x=\dfrac{a^2}{x}+3a

x(x+2)(x1)=a2x+3ax(x+2)(x-1)=\dfrac{a^2}{x}+3a

sketch LHS

sketch RHS

find points of intersection
Reply 4
thats not an exact solution. u cheater! All you can find doing this is the number of solutions and a range of values each solution takes.
(edited 13 years ago)
Unparseable latex formula:

\\ x^3(x+1) = (x+a)(2x+a) \\[br]\implies (x^2 - x - a)(x^2 + 2x + a) = 0

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