Question

15x²-28=x
factorisation method

Answer 1

$15 {x}^{2} - 28 = x \\ 15 {x}^{2} - x - 28 = 0 \\ 15 {x}^{2} - 21x + 20x - 28 = 0 \\ 3x(5x - 7) + 4(5x - 7) = 0 \\ (3x + 4)(5x - 7) = 0 \\ x = - 4 \div 3 \: x = 7 \div 5$

hence x=-4/3 & x= 7/5