Year 12s: what will be the first way you research your future options? >>

M2 integration/differentiation

Im doing 3 c and Im unsure what method I should use to solve t^4 -6t^2 +8 =0. In my attempt i used the factor theorem to determine that t=+/-2 is a possible solution, and tried to divide the polynomial my (t-2) however I got a remainder at the end. This seems like a lot to do for three marks, is this the method we're expected to use?

IMG_20160508_183724.jpg459.9KB

IMG_20160508_183646.jpg417.4KB

Reply 1

Zacken

Original post by pineneedles

No, you're meant to recognise that if you let u = t^2 then you get u^2 - 6u + 8 = 0 which is an easy quadratic. Then you can back-sub u = t^2 and solve for t. (assuming that your t^4 - 6t^2 + 8 = 0 is right in the first place, haven't checked.)