Question

factorise a(a+b-c) -bc

Answer 1

your answer is in the referred attachment.

Answer 2

a(a+b+c) - bc

>a^2+ ab+ac-bc

>a^2 +a(b+c) -bc

Here , if we compare the above statement with standard quadratic equation we get

a=1, b=(b+c) c= (-bc)

by quadratic formula

(-b +- √b²-4ac)/2a

the calculation is done in the above image