Question

m^4 - 7m^2 -18 factorise

Answer 1

Answer:

$( {m}^{2} + 2)( {m}^{2} - 9).$

Step-by-step explanation:

${m}^{4} - 7 {m}^{2} - 18 = {m}^{4} - 9 {m}^{2} + 2 {m}^{2} - 18 \\ \\ = {m}^{2} ( {m}^{2} - 9) + 2( {m}^{2} - 9) \\ \\ = ( {m}^{2} + 2)( {m}^{2} - 9).$