Question

Se da numarul a=$2^{1990}$-$2^{1989}$-$2^{1988}$.Aflati x din proportia:$\frac{a}{x} }$=$\frac{ 4^{993} }{0,25} }$.

Answer 1

a=2∧1990-2∧1989-2∧1988
a=2∧1988(2²-2-1)
a=2∧1988·(4-2-1)
a=2∧1988
a/x=4∧993/0,25
2∧1988/x=2∧1996/25/100
2∧1988/x=2∧1996/1/4
2∧1988/x=2∧1996·2²
2∧1998/x=2∧1998
In concluzie
x=1