Answer:
12
Explanation:
We are given that two equations
![y=-2x+4](https://img.qammunity.org/2020/formulas/mathematics/middle-school/gnzxe17uexzh53kp1raoo5405reqq5zuah.png)
![6x+3y=](https://img.qammunity.org/2020/formulas/mathematics/middle-school/smnchgbpqocdzw5j4itq9xgwegdbwnqqy7.png)
We have to find the value in the blank space when we place that value then system of equations have infinitely many solutions
Equation I can be written as
![2x+y-4=0](https://img.qammunity.org/2020/formulas/mathematics/middle-school/6i2tvmenqx5579v3uis0iqzul0phzcnruj.png)
Let a be the value that placed in blank space and system have infinitely many solutions
Then
![6x+3y-a=0](https://img.qammunity.org/2020/formulas/mathematics/middle-school/vpotq66x35v8gzmoppmgpahozneb3fqxj3.png)
We know that condition of infinite solutions
![(a_1)/(a_2)=(b_1)/(b_2)=(c_1)/(c_2)](https://img.qammunity.org/2020/formulas/mathematics/high-school/czf0u5va4zc73opwmtl57j1frwov3wgk9t.png)
Substitute the values then we get
![(2)/(6)=(-4)/(-a)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/h3i0n9uxmk8x1hiz3t2s54vm1n6ejdphj9.png)
![(1)/(3)=(4)/(a)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xp02e4svx5rbe315pgfclybul17k0eeebm.png)
![a=4* 3](https://img.qammunity.org/2020/formulas/mathematics/middle-school/o3a8wr5xk6joo16f5wqowe619ql6xyj3t5.png)
a=12
Hence, when we placed 12 in the box then system of equations would have infinitely many solutions .
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