To solve the equation \(|5x + 9| = 4x\), we need to consider two cases due to the absolute value: one where the expression inside the absolute value is non-negative, and one where it is negative. This will give us two separate linear equations to solve for \(x\).
- Case 1: \(5x + 9 \geq 0\), which simplifies to \(5x + 9 = 4x\).
- Case 2: \(5x + 9 < 0\), which simplifies to \(-(5x + 9) = 4x\).
Solve each equation separately and check the solutions against the conditions for each case.
Para el primer caso, donde \(5x + 9 = 4x\), simplificamos la ecuación:
\[
5x + 9 = 4x
\]
Restando \(4x\) de ambos lados, obtenemos:
\[
5x - 4x + 9 = 0 \implies x + 9 = 0 \implies x = -9
\]
Verificamos si \(x = -9\) satisface la condición \(5x + 9 \geq 0\):
\[
5(-9) + 9 = -45 + 9 = -36 < 0
\]
Por lo tanto, \(x = -9\) no es una solución válida.
Para el segundo caso, donde \(-(5x + 9) = 4x\), simplificamos la ecuación:
\[
-5x - 9 = 4x
\]
Sumando \(5x\) a ambos lados, obtenemos:
\[
-9 = 4x + 5x \implies -9 = 9x \implies x = -1
\]
Verificamos si \(x = -1\) satisface la condición \(5x + 9 < 0\):
\[
5(-1) + 9 = -5 + 9 = 4 \geq 0
\]
Por lo tanto, \(x = -1\) no es una solución válida.
No encontramos soluciones válidas para la ecuación \(|5x + 9| = 4x\).
\(\boxed{\text{No hay solución}}\)