 ## Question

secondary 2 | Maths

Anyone can contribute an answer, even non-tutors.

##### Myth

chevron_right chevron_right

Not sure how to do this

Date Posted: 9 months ago
Views: 52
Snell
9 months ago
srly ? ? ?

lol

y² = 3 or y² = 1

.
.
.
J
9 months ago
y⁴ - 4y² + 3 = 0

now notice that y⁴ = (y²)²

So

(y²)² - 4(y²) + 3 = 0

It is actually now in the form of a quadratic equation. You can use a substitution like u = y² if you find it difficult to visualise.

Then,

(y² - 1)(y² - 3) = 0

y² - 1 = 0 or y² - 3 = 0

y² = 1 or y² = 3

y = ± 1 or y = ± 3 (rejected as y is integer)

So y = 1 or y = -1
Eric Nicholas K
9 months ago
Probably the quadratic idea does not appear to be “automatic” for Sec 2 students since they think of quadratic as ax2 + bx + c = 0 and not other forms like ax4 + bx2 + c = 0 or ax6 + bx3 + c = 0.
Nalin Sharma
9 months ago
No this is correct, my bad.
J
9 months ago
Not automatic for most at upper levels too. This question is probably meant to broaden their horizons, and might come out in exams as a way to test them/differentiate between A1s and A2s 