Question

Find the value of x and y​

Answer 1

x = 1

y = -3

Explanation:

cos(pi) = -1

so many ways :

sqrt(0.5/2) = sqrt(0.5/2 × 8/8) = sqrt(4/16)

= sqrt(0.5/2 × 18/18) = sqrt(9/36)

= sqrt(1/4) = 1/2

"nicest" approach (all integers) :

3x² = sqrt(9)

3x² = 3

x² = 3/3 = 1

x = 1

2y = sqrt(36)

2y = 6

y = 6/2 = 3

one of them has to be negative (because cos(pi) = -1), so it has to be y, because 3x² cannot be negative with real numbers.

so, y = -3

-1 × 3×1²/(2×-3) = sqrt(0.5/2) = 1/2

-1 × 3/-6 = 1/2

3/6 = 1/2

1/2 = 1/2

correct