.If a + b = 10 and ab = 21, then the value of $(a-b)^{2}$ is
1). 15
2). 16
3). 17
4). 18
1. If a + b = 1, then the value of a3 + b3 + 3ab is equal to
2. If x+$\frac{1}{x}$ =5, then the value of $\frac{5x}{x^{2}+5x+1}$ is
3. If a - b = 4 and ab = -3, then what is the value of $a^{3}-b^{3}$?
5. If $4x^{2}$ = $15^{2}$ - $9^{2}$ , then value of x is
7. ‘O’ is the circumcentre of triangle ABC. If $\angle BAC$ = $50^{0}$ then $\angle OBC$ is