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If [5x+87y+310x+12]=[23y+150]\left[\begin{array}{cc}5 x+8 & 7 \\ y+3 & 10 x+12\end{array}\right]=\left[\begin{array}{cc}2 & 3 y+1 \\ 5 & 0\end{array}\right], then the value of 5x+3y5 x+3 y is equal to :

Solution

✅ Correct Option: 4

When two matrices are equal, every corresponding element must be equal.

[5x+87y+310x+12]=[23y+150]\left[\begin{array}{cc}5 x+8 & 7 \\ y+3 & 10 x+12\end{array}\right]=\left[\begin{array}{cc}2 & 3 y+1 \\ 5 & 0\end{array}\right]

Comparing corresponding elements:

Top-left: 5x+8=25x + 8 = 2

Top-right: 7=3y+17 = 3y + 1

Bottom-left: y+3=5y + 3 = 5

Bottom-right: 10x+12=010x + 12 = 0


From the bottom-left element:

y+3=5y + 3 = 5

y=2y = 2

We can verify with the top-right element: 7=3(2)+1=77 = 3(2) + 1 = 7 ✓


From the bottom-right element:

10x+12=010x + 12 = 0

10x=−1210x = -12

x=−1210=−65x = \dfrac{-12}{10} = \dfrac{-6}{5}

We can verify with the top-left element: 5(−65)+8=−6+8=25\left(\dfrac{-6}{5}\right) + 8 = -6 + 8 = 2 ✓


Now calculate 5x+3y5x + 3y:

5x+3y=5(−65)+3(2)5x + 3y = 5\left(\dfrac{-6}{5}\right) + 3(2)

=−6+6= -6 + 6

=0= 0

Final Answer: 00

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