Answer:
the answer is 5×9+2=47
Step-by-step explanation:
the answer is 47
X^-1 = 1 / x ;
( x + 1 )^-1 = 1 / ( x + 1 ) ;
Then, x^-1 - ( x + 1 )^-1 = 1 / x - 1 / ( x + 1 ) = ( x + 1 ) / [x( x + 1 )] - x / [x( x + 1 )] = ( x + 1 - x ) /[x( x + 1 )] = 1 / [x( x + 1 )];
Finally, (1 / [x( x + 1 )])-2 =[x( x + 1 )]^2 = (x^2)[( x + 1 )^2] ;
7.2
a^2 + b^2 = c^
a=6
b=4
36+16=c^2
52=c2
root both sides
7.2=c
Think: where did that 4 come from? Hint: the cube root of 64 is 4; the cube of 4 is 64.
The first one can be done by Pythagoras theorem such as

then

then

The second one can also done by Pythagoras theorem, note that this is isosceles triangle so

, again by using Pythagoras theorem

then

then

For the last one can also done by property of 30-60-90 triangle.
