ENEM 2015 Matemática #26 - Porcentagem e Equação Quadrática (questão difíci)

🔗 Buy the ENEM Mathematics 800+ course: https://pay.hotmart.com/C97770743H Learn about our platform at http://www.matematicario.com.br People got confused with this question about percentages, geometry and quadratic equations from ENEM 2015. Come with me! ENEM 2015 QUESTION 161 A factory produces sun protection meshes to be applied to windows, in order to reduce the passage of light, from plastic tapes intertwined perpendicularly. In the vertical and horizontal directions, tapes of 1 millimeter width are applied, such that the distance between them is (d-1) millimeters, as shown in the figure. The material used does not allow the passage of light, that is, only the ray of light that hits the gaps left by the intertwining can pass through this protection. The glass coverage rate is the percentage of the area covered by the mesh strips, which are placed parallel to the edges of the glass. This industry received an order for a solar protection mesh to be applied to a rectangular glass measuring 5 cm wide by 9 m long. The measurement of d, in millimeters, for the mesh coverage rate to be 75% is Matemática Rio is a channel with online math classes, completely free and creative! Learn interesting content in a few minutes! Created by Professor Rafael Procopio: Postgraduate degree in Mathematics Teaching (UFRJ); Mathematics teacher in the public school system of Rio de Janeiro. Matemática Rio on social media: Facebook:   / matematicario   Twitter:   / matematicario   Google+: http://www.google.com/+MatematicaRio