Question

(h) 20 - [x2 – 6 {(2x + 3) - (2x + 7)}]



simplify​

Answer 1

$20 - ( {x}^{2} - 6((2x + 3) - (2x + 7))) \\ = 20 - ( {x}^{2} - 6(2x + 3 - 2x - 7)) \\ = 20 - ( {x}^{2} - 6( - 4)) \\ = 20 - ( {x}^{2} + 24) \\ = 20 - {x}^{2} - 24 \\ = - {x}^{2} - 4 \\ - {x}^{2} - 4 = 0 \\ - ( {x}^{2} + 4) = 0 \\ {x}^{2} + 4 = 0 \\ {x}^{2} = - 4 \\ \sqrt{ {x}^{2} } = \sqrt{ - 4 } \\ x = - 2$