Question

B = am - an + bm - bn với a + b = 9 , m - n = 27

Answer 1

B=am-an+bm-bn

B=a(m-n)+b(m-n)

=> B=a.27+b.27

B=27(a+b)

=> B=27.9

B=243

Answer 2

\(B=am-an+bm-bn=a\left(m-n\right)+b\left(m-n\right)=\left(a+b\right)\left(m-n\right)=9.27=243\)

Answer 3

B = am - an + bm - bn

B = a(m-n) + b(m-n)

B = (a+b) (m-n)

thay số vào ta có:

B = (a+b) (m-n)

B =  9 * 27

B =243