If ab = 21 and $$\frac{{{{\left( {a + b} \right)}^2}}}{{{{\left( {a - b} \right)}^2}}}$$ = $$\frac{{25}}{4}{\text{,}}$$ then the value of a2 + b2 + 3ab is?
A. 115
B. 121
C. 125
D. 127
Answer: Option B
Solution(By Examveda Team)
$$\eqalign{ & \frac{{{{\left( {a + b} \right)}^2}}}{{{{\left( {a - b} \right)}^2}}} = \frac{{25}}{4} \cr & \Rightarrow \frac{{a + b}}{{a - b}} = \frac{5}{2} \cr & \Rightarrow {\text{By Componendo & Dividendo}} \cr & \Rightarrow \frac{{a + b + a - b}}{{a + b - a + b}} = \frac{{5 + 2}}{{5 - 2}} \cr & \Rightarrow \frac{{2a}}{{2b}} = \frac{7}{3} \cr & \Rightarrow \frac{a}{b} = \frac{7}{3} \cr & {\text{Now, the value of}} \cr & \Rightarrow {a^2} + {b^2} + 3ab \cr & \Rightarrow {7^2} + {3^2} + 3.7.3 \cr & \Rightarrow 49 + 9 + 63 \cr & \Rightarrow 121 \cr} $$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. $$\frac{8}{6}$$
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