Jika Matris A=( A b) ,b =(2c 2d) c d. a+c b+d dan det A)=5 ,maka det (b)=???

A = (a .. b)
...... (c .. d)
det A = 5 => ad - bc = 5 atau bc - ad = -5

B = (2c ........... 2d)
...... (a + c ... b + d)
det B = 2c(b + d) - 2d(a + c)
= 2bc + 2cd - 2ad - 2cd
= 2bc - 2ad
= 2(bc - ad)
= 2(-5)
= -10