70 Вправа 70Алгебра 8 клас Тарасенкова 2025 · § 1 · стор. 21

70. Визначте ОДЗ кожної змінної виразу.

1) ${\displaystyle \frac{2b-3c}{7bc}}$;

${\displaystyle 7bc=}$${\displaystyle 0}$; ${\displaystyle b=}$${\displaystyle 0}$ або ${\displaystyle c=}$${\displaystyle 0}$;

ОДЗ: ${\displaystyle b\ne 0}$, ${\displaystyle c\ne 0}$;

2) ${\displaystyle 3ab:{\left((2-a)b\right)}^2}$;

${\displaystyle {\left((2-a)b\right)}^2=}$${\displaystyle 0}$;

${\displaystyle (2-a)b=}$${\displaystyle 0}$;

${\displaystyle 2-a=}$${\displaystyle 0}$ або ${\displaystyle b=}$${\displaystyle 0}$;

${\displaystyle a=}$${\displaystyle 2}$ або ${\displaystyle b=}$${\displaystyle 0}$;

ОДЗ: ${\displaystyle a\ne 2}$, ${\displaystyle b\ne 0}$;

3) ${\displaystyle \frac{6xy}{(3x-8)(2x+6)}}$;

${\displaystyle (3x-8)(2x+6)=}$${\displaystyle 0}$;

${\displaystyle 3x-8=}$${\displaystyle 0}$ або ${\displaystyle 2x+6=}$${\displaystyle 0}$;

${\displaystyle 3x=}$${\displaystyle 8}$ або ${\displaystyle 2x=}$${\displaystyle -6}$;

${\displaystyle x=}$${\displaystyle \frac{8}{3}=}$${\displaystyle 2\frac{2}{3}}$ або ${\displaystyle x=}$${\displaystyle -3}$;

ОДЗ: ${\displaystyle x\ne 2\frac{2}{3}}$, ${\displaystyle x\ne -3}$; ${\displaystyle y}$ — будь-яке число;

4) ${\displaystyle 3y:(y^2-8y+16)}$;

${\displaystyle y^2-8y+16=}$${\displaystyle 0}$;

${\displaystyle {(y-4)}^2=}$${\displaystyle 0}$;

${\displaystyle y=}$${\displaystyle 4}$;

ОДЗ: ${\displaystyle y\ne 4}$.