Answer:
448
Step-by-step explanation:
4x +7y = 28 and xy = 6 (Given)
[tex] {(4x + 7y)}^{2} = {(4x)}^{2} + {(7y)}^{2} + 2(4x)(7y) \\ \\ \implies \: {(4x + 7y)}^{2} = {16x}^{2} + {49y}^{2} + 56xy\\ \\ \implies \: {(28)}^{2} = {16x}^{2} + {49y}^{2} + 56(6) \\ \\ \implies \: 784 = {16x}^{2} + {49y}^{2} + 336 \\ \\ \implies \: {16x}^{2} + {49y}^{2} = 784 - 336\\ \\ \implies \: \huge \orange{ {16x}^{2} + {49y}^{2} =448}[/tex]
