24
22
-12
-21
Correct answer is D
x \(\ast\) y = x + y - xy
(x \(\ast\) 2) + (x \(\ast\) 3) = 68
= x + 2 - 2x + x + 3 - 3x
= 86
3x = 63
x = -21
Express \((0.0439 \div 3.62)\) as a fraction....
If \(\frac{x}{a + 1}\) + \(\frac{y}{b}\) = 1. Make y the subject of the relation....
Express the product of 0.007 and 0.057 to two significant figures ...
Find the values of k in the equation 6k2 = 5k + 6...
If f(x - 2) = 3x2 + 4x + 1. Find the area of the sector...
If \(y \propto \frac{1}{\sqrt{x}}\) and x = 16 when y = 2, find x when y = 24...