Question

a) x³ + 3 . 14 = 5². 10 + 8 c) 17x − 5 = 5 . (2x + 1) − 3 d) 6 . (3x + 5) = 3 . (20 + x) e) x² − (36 + 2 . 5) = 2 . 3²

Answer 1

a)

${x}^{3} + 3 \times 14 = {5}^{2} \times 10 + 8 \\ {x}^{3} + 42 = 25 \times 10 + 8 \\ {x}^{3} = 258 - 42 \\ {x}^{3} = 216 \\ x = \sqrt[3]{216} \\ x = 6$

c)

$17x - 5 = 5 \times (2x + 1) - 3 \\ 17x - 5 = 10x + 5 - 3 \\ 7x = 7 \\ x = 1$

d)

$6 \times (3x + 5) = 3 \times (20 + x) \\ 2(3x + 5) = 20 + x \\ 6x + 10 = 20 + x \\ 5x = 10 \\ x = 2$

e)

${x}^{2} - (36 + 2 \times 5) = 2 \times {3}^{2} \\ {x}^{2} - 46 = 2 \times 9 \\ {x}^{2} - 46 = 18 \\ {x}^{2} = 18 + 46 \\ {x}^{2} = 64 \\ x = \sqrt{64} \\ x = 8 \: \: \: o \: \: \: x = - 8$