<![CDATA[This study examines the influence of product knowledge, brand image, and brand trust on purchasing decisions among consumers of isotonic drink PRT. The research aims to identify the partial and simultaneous effect of these variables on consumer buying behavior. A quantitative approach with an explanatory research design was applied to explain causal relationships. The population consisted of isotonic drink PRT consumers in Sidoarjo City, with 130 respondents selected using purposive sampling. Data were collected through a structured questionnaire measured using a Likert scale. The collected data were analyzed using multiple linear regression with the assistance of SPSS software. Several statistical procedures were conducted, including validity tests, reliability tests, classical assumption tests, and hypothesis testing using t-tests and F-tests. The results indicate that product knowledge has a positive and significant effect on purchasing decisions, showing that consumers who understand product characteristics are more likely to make purchases. Brand image also has a positive and significant influence, reflecting the importance of favorable perceptions toward the brand. Brand trust demonstrates the strongest positive effect, indicating that consumer confidence plays a crucial role in purchasing decisions. Simultaneously, product knowledge, brand image, and brand trust significantly influence purchasing decisions. The adjusted R-squared value of 0.777 indicates that 77.7 percent of variations in purchasing decisions are explained by the independent variables. These findings suggest that companies should improve consumer knowledge, maintain a positive brand image, and strengthen brand trust. Results strengthen practical marketing strategy.]]>
