Solve the following quadratic equations by factorisation method.
(i) `x^(2) +8x+15=0`
(ii) `5m^(2) - 22m - 15= 0 `

Answer

(i) `-5,-3` are the roots of the given quadratic equation.
(ii) `5, - (3)/(5)` are the roots of the given quadratic equation.

Explanation

(ii) `x^(2) + 8x + 15+=0`
`:. X^(2)+ 5x+ 3x+ 15= 0 `
`:. X( x+5) + 3 (x+ 5) = 0 `
`:. ( x + 5 ) ( x + 3) = 0 `
` :. X + 5 = 0 ` or ` x + 3 = 0 `
`:. x = -5` or `x= - 3 `
(ii) `5m^(2) - 22m - 15 = 0 `
`:. 5m^(2) - 25m + 3m - 15= 0 `
`:. 5m ( m - 5) + 3 ( m -5) = 0 `
`:. ( m - 5) ( 5m + 3 ) = 0 `
`:. m - 5 = 0 ` or ` 5m + 3 = 0 `
` :. m = 5 ` or ` 5m = - `
` :. m = - (3)/(5)`