Question

(b) x =- is the solution of 16x2 + 4x -5 = 205
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Mathematics-6​

Answer 1

Answer:

$16 {x}^{2} + 4x - 5 = 205 \\ 16 {x}^{2} + 4x = 205 + 5 \\ 16 {x}^{2} + 4x = 210 \\ 16 {x}^{2} + 4x - 210 = 0 \\ 2(8 {x}^{2} + 2x - 105) = 0 \\ 8 {x}^{2} + 2x - 105 = 0 \\ 8 {x}^{2} + 30x - 28x - 105 = 0 \\ 2x(4x + 15) - 7(4x + 15) = 0 \\ (4x + 15)(2x - 7) = 0 \\ 4x + 15 = 0 \: \: \: or \: \: \: 2x - 7 = 0 \\ 4x = - 15 \: \: \: or \: \: \: 2x = 7 \\ \boxed{x = \underline{ \underline{\frac{ - 15}{4}}} \: \: \: or \: \: \: x = \underline{ \underline{\frac{7}{2}}} }$