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If (9x - 3y) = 96 and 4x : 3y = 20 : 21, then find the value of (2x² + 3y²).
Question

If (9x - 3y) = 96 and 4x : 3y = 20 : 21, then find the value of (2x² + 3y²).

A.

2756

B.

3341

C.

3152

D.

2280

Correct option is C

Given:
Equation 1: 9x - 3y = 96
Equation 2: 4x3y=2021\frac{4x}{3y} = \frac{20}{21}​​
Solution:
From the second equation, find the ratio of x to y:
xy=20×321×4\frac{x}{y} = \frac{20 × 3}{21 × 4}​​
xy=6084\frac{x}{y} = \frac{60}{84}​​
xy=57\frac{x}{y} = \frac{5}{7}​​
Let x = 5k and y = 7k.
Substitute these into the first equation:
9(5k) - 3(7k) = 96
45k - 21k = 96
24k = 96
k =9624 \frac{96}{24}​​
k = 4
Now find the actual values of x and y:
x = 5 × 4 = 20
y = 7 × 4 = 28
Now calculate the value of 2x2+3y2:2x^2 + 3y^2:​​
2(20)2+3(28)2 2(20)^2 + 3(28)^2​​
= 2(400) + 3(784)
= 800 + 2352
= 3152
Final Answer
So the correct answer is (c)

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