Tìm số tự nhiên x, biết :
a, x – 5 = 50 : 2
b, 30 : x – 7 = 24 : 3
c, 4x + 7x = 11 mũ 2
d, ( x – 12 ) . ( x + 13 ) = 0
Tìm số tự nhiên x, biết :
a, x – 5 = 50 : 2
b, 30 : x – 7 = 24 : 3
c, 4x + 7x = 11 mũ 2
d, ( x – 12 ) . ( x + 13 ) = 0
$\text{Chào bạn. Bạn tham khảo nhé !}$
$\text{Bài làm :}$ $\text{Tìm số tự nhiên x, biết :}$
$\text{a, x – 5 = 50 ÷ 2}$
$\text{x – 5 = 25}$
$\text{x = 25 + 5}$
$\text{x = 30}$
$\text{b, 30 ÷ x – 7 = 24 ÷ 3}$
$\text{30 ÷ x – 7 = 8}$
$\text{x – 7 = 30 ÷ 8}$
$\text{x – 7 = 3,75}$
$\text{x = 3,75 + 7}$
$\text{x = 10,75}$
$\text{c, 4x + 7x = 11^2}$
$\text{4x + 7x = 121}$
$\text{( 4 + 7 ) . x = 121}$
$\text{11 . x = 121}$
$\text{x = 121 ÷ 11}$
$\text{x = 11}$
$\text{d, ( x – 12 ) . ( x + 13 ) = 0
$\text{x . 13 – ( 12 + 1 ) = 0}$
$\text{x . 13 – 13 = 0}$
$\text{x . 0 = 0}$
$\text{x = 0 ÷ 0}$
$\text{x = 0}$
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Bạn tham khảo :
a.
$x – 5 = 50:2$
$x – 5= 25$
$x =30$
b .
$30:x -7 = 24:3$
$30:x -7 =8$
$30:x = 15$
$x =2$
c .
$4x+7x=11^2$
$11x = 121$
$x = 11$
d .
$(x-12)(x+13) =0$
⇒ \(\left[ \begin{array}{l}x-12=0\\x+13=0\end{array} \right.\)
⇒ \(\left[ \begin{array}{l}x= 12\\x=-13\end{array} \right.\)
Vậy $x∈ \text{{12;(-13)}}$