Question

Va rog sa ma ajutati .Fie functia f(x) = 5x -1.Demonstrati ca f(11 supra 7 ) - f( 4 supra 7 ) = f( 13 supra 9 ) - f( 4 supra 9 )

Answer 1

f($\frac{11}{7}$) = $\frac{55}{7}$ -1 = $\frac{48}{7}$
f( $\frac{4}{7}$) = $\frac{20}{7}$ -1 = $\frac{13}{7}$
f( $\frac{13}{9}$) = $\frac{65}{9}$ -1 = $\frac{56}{9}$
f( $\frac{4}{9}$) = $\frac{20}{9}$ -1 = $\frac{11}{9}$

$\frac{48}{7}$ -  $\frac{13}{7}$ =  $\frac{56}{9}$ -  $\frac{11}{9}$
$\frac{35}{7}$ =  $\frac{45}{9}$ 
5 = 5