JEE Main 2022 · 27 Jun · Shift 2 · Mathematics Q19

MathematicsSingle correct+4 / -1Question 19 of 90

$\alpha=\sin36°$ is a root of which of the following equation?

16x^4-10x^2-5=0

16x^4+20x^2-5=0

16x^4-20x^2+5=0

16x^4-10x^2+5=0

Answer and worked solution

Official answer: C

Value. $\sin^236°=\dfrac{5-\sqrt5}8$ , a root of $8s=5\pm\sqrt5$ , i.e. $64s^2-80s+20=0$ .

With $s=x^2$ : $16x^4-20x^2+5=0$ .

(C)

JEE Main 2022 · 27 Jun · Shift 2, Mathematics question 19