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If x+ y - 7 = 0 and 3x + y -13 = 0, then what is \( \Large 4x^{2} + y^{2} + 4xy\) equal to?


A) 75

B) 85

C) 91

D) 100

Correct Answer:
D) 100

Description for Correct answer:

We have x+y-7=0

x + y = 7 ...(i)

and 3x + y - 13 = 0

= 3x + y = 13 ...(ii)

B subtracting Eq. (i)from Eq. (ii), we get

3x + y = 13 ...(i)

x + y = 7 ...(iI)

2x = 6

Therefore, x = 3

On putting the value of x in q. (i), we get

3 + y = 7

Therefore, y = 4

Now,

\( \Large 4x^{2}+y^{2}+4xy \)

\( \Large 4 \times \left(3\right)^{2}+ \left(4\right)^{2}+4 \times 3 \times 4 \)

\( \Large 4 \times 9+16+48 \)

\( \Large 36+16+48=100 \)


Part of solved Linear Equations questions and answers : >> Aptitude >> Linear Equations




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