a, = 3x - 2x = x
b, = 3.( 3 - a ) = 9 - 3a
c, = a.( a - 5 ) = a^2 - 5a
d, = 2a/3 . 3a/2 = a . a = a^2
e, = 1/a-b . a^2 . ( a - b ) = a^2
e chỉ bt rút gọn đến đây th ạ
mong a chj thông cảm ạ
\(a,\sqrt{9x^2}-2x\\ =\left|3x\right|-2x\\ =-3x-2x\left(x< 0\right)\\ =-5x\\ b,\sqrt{9\left(3-a\right)^2}\\ =\left|3\left(3-a\right)\right|\\ =3\left|3-a\right|\\ =3\cdot\left(a-3\right)\\ c,\sqrt{a^2\left(a-5\right)^2}\\ =\left|a\left(a-5\right)\right|\\ =\left|a\right|\cdot\left|a-5\right|\\ =\left(-a\right)\cdot\left(5-a\right)\\ =a^2-5a\)
\(d,\sqrt{\dfrac{2a}{3}}\cdot\sqrt{\dfrac{3a}{2}}\\ =\sqrt{\dfrac{2a}{3}\cdot\dfrac{3a}{2}}\\ =\sqrt{a^2}\\ =\left|a\right|\\ =a\left(a\ge0\right)\\ e,\dfrac{1}{a-b}\sqrt{a^4\left(a-b\right)^2}\\ =\dfrac{1}{a-b}\cdot\left|a-b\right|\cdot a^2\\ =\dfrac{1}{a-b}\cdot\left(-a+b\right)\cdot a^2\\ =\left(-1\right)\cdot a^2=-a^2\)
