Answer: h = 9
Step-by-step explanation: A system of linear equations is consistent when it has at least one solution.
The matrix given is:
![\left[\begin{array}{ccc}-15&21&h\\5&-7&-3\end{array}\right]](https://img.qammunity.org/2021/formulas/mathematics/college/uksgnok907u7vbehfjejl27ksd5rxmag7h.png)
Transform this matrix in a row-echelon form:
![\left[\begin{array}{ccc}-15&21&h\\0&0&-9+h\end{array}\right]](https://img.qammunity.org/2021/formulas/mathematics/college/sm96zteanvurb09yy21ugdo0hy8pxl0w50.png)
For this row-echelon form to have solutions:
-9 + h = 0
h = 9
For this system to be consistent: h = 9.