find the value of `(2. 8 a^2b^3)xx(3/7 a b)x(4 a b^2)=0.` when `a=0.5` and `b=0.8`

Find the value of (2.3a^(5)b^(2)) xx(1.2 a^(2)b^(2)) when a = 1 and b = 0.5

Find the value of 3^(2^(4^(0^(7^(8)))))+8^(3^(2^(0^(4^(7)))))

Evaluate ( 2^8 times a^5 times b^3 )/ ( ( 4^2 times a^2 times b )

Find the value of a , b , c , d , x , y from the following matrix equation . ({:(d , 8) , (3b , a):}) + ({:(3 , a) , (-2 , -4):})= ({:(2 , 2a) , (b , 4c):}) + ({:(0 , 1) , (-5 , 0):})

Find the value of the expressions, when a= -1" and "b= 3 5a^(2)+4ab^(2)-8a^(2)b .

If (a+3b)*(7a-5b)=0 and (a-4b)*(7a-2b)=0 . Then, the angle between a and b is