Solve x^4+2x^2-3=0
The trick with this question is noticing the hidden quadratic as quartic equations are unsolvable at A-level.
Letting u=x^2 the question becomes u^2+2u-3=0 which most students would be able to solve.
To factorise this then we must find two numbers that add to 2 and multiply to give -3, i.e. 3 and -1.
Therefore factorising this becomes: (x+3)(x-1)=0 x therefore equals -3 and 1
BS
Related Maths A Level answers
All answers ▸Differentiate 2x^3 - xy^2 - 4
The line AB has equation 3x + 5y = 7. Find the gradient of line AB.
A tank is filled with water up to the height H0. At the bottom of the tank, there is a tap which is opened at t=0. How does the height of liquid change with time?(Hint: dH/dt is proportional to -H)
I struggle to simplify the following equation: (see answer)