If x + y = 4, x2 + y2 = 14 and x > y. Then the correct value of x and y is?
A. $$2 - \sqrt 2 ,\sqrt 3 $$
B. $$3,1$$
C. $$2 + \sqrt 3 ,2 - \sqrt 3 $$
D. $$2 + \sqrt 3 ,2\sqrt 2 $$
Answer: Option C
Solution(By Examveda Team)
$$\eqalign{ & {x^2} + {y^2} = 14 \cr & x + y = 4\,.............(i) \cr & {\text{Squaring both sides}} \cr & \Rightarrow {x^2} + {y^2} + 2xy = 16 \cr & \Rightarrow 14 + 2xy = 16 \cr & \Rightarrow 2xy = 2 \cr & \Rightarrow xy = 1 \cr & \Rightarrow {x^2} + {y^2} = 14 \cr} $$Subtracting (2xy) from both sides
$$\eqalign{ & \Rightarrow {x^2} + {y^2} - 2xy = 14 - 2xy \cr & \Rightarrow {\left( {x - y} \right)^2} = 14 - 2 \times 1 \cr & \Rightarrow x - y = \sqrt {12} \cr & \Rightarrow x - y = 2\sqrt 3 \,.........(ii) \cr & {\text{Solve equation (i) and (ii)}} \cr & \Rightarrow y = 2 - \sqrt 3 \cr & \Rightarrow x = 2 + \sqrt 3 \cr} $$
Related Questions on Algebra
If $$p \times q = p + q + \frac{p}{q}{\text{,}}$$ then the value of 8 × 2 is?
A. 6
B. 10
C. 14
D. 16
A. $$1 + \frac{1}{{x + 4}}$$
B. x + 4
C. $$\frac{1}{x}$$
D. $$\frac{{x + 4}}{x}$$
A. $$\frac{{20}}{{27}}$$
B. $$\frac{{27}}{{20}}$$
C. $$\frac{6}{8}$$
D. $$\frac{8}{6}$$
Join The Discussion