+21 Given that $3x + y = 10$ and $x + 3y = 14$, find $10x^2 + 12xy + 10y^2$.
+128408 Given that 3x + y = 10 and x + 3y = 14, find 10x^2 + 12xy + 10y^2.
3x + y = 10 (1)
x + 3y = 14 ⇒ -3x - 9y = -42 (2) add (1) and (2)
-8y = -32 divide through by -8
y = 4
So using (1) 3(x) + 4 = 10
3(x) = 6
x = 2
So
10x^2 + 12xy + 10y^2 =
10 (2)^2 + 12 (2)(4) + 10(4)^2 =
40 + 96 + 160 =
296
