Question

if 4a-5b=6 and ab=8 then find the value of 16a2+25b2

Answer 1

$4a - 5b = 6 \\ sobs \: \\ 16 {a}^{2} + 25 {b}^{2} - 40ab = 36 \\ 16 {a}^{2} + 25 {b}^{2} - 4 0(8) = 36 \\ 16 {a}^{2} + 25 {b}^{2} = 36 + 40(8) \\ = 36 + 320 \\ = 356$

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