Question

6 Află numerele necunoscute din expresiile de mai jos.
a. (x + 20): 12 + 68 = 78
d. 101 x (101 - (101 - 102:x)] = 202
b. (x + 282-75) : 2 = 104
e. 369 - [(x + 112):5 + 113] = 434
c. xx4:10 + 101 = 133
f. 104 : [(x-3 x 8) 2:8] = 13
Coroana

Answer 1

a)

$(x + 20) \div 12 + 68 = 78$

$\frac{x + 20}{12} + 68 = 78$

$x + 20 + 816 = 936$

$x + 836 = 936$

$x = 936 - 836$

$x = 100$

d)

$101 \times (101 - (101 - 102 \div x)) = 202$

$101 \times (101 - (101 - \frac{102}{x})) = 202$

$101 \times (101 - 101 + \frac{102}{x}) = 202$

$101 \times \frac{102}{x} = 202$

$\frac{10302}{x} = 202$

$10302 = 202x$

$x = 51$

b)

$(x + 282 - 75) \div 2 = 104$

$(x + 207) \div 2 = 104$

$\frac{x + 207}{2} = 104$

$x + 207 = 208$

$x = 208 - 207$

$x = 1$

e)

$369 - ((x + 112) \div 5 + 113) = 434$

$369 - ( \frac{x + 112}{5} + 113) = 434$

$369 - \frac{x + 112}{5} - 113 = 434$

$256 - \frac{x + 112}{5} = 434$

$1280 - (x + 112) = 2170$

$1280 - x - 112 = 2170$

$1168 - x = 2170$

$- x = 2170 - 1168$

$- x = 1002$

$x = - 1002$

c)

$x \times 4 \div 10 + 101 = 133$

$\frac{4}{10}x + 101 = 133$

$\frac{2}{5}x + 101 = 133$

$2x + 505 = 665$

$2x = 665 - 505$

$2x = 160$

$x = 80$

f)

$104 \div (( \times - 3 \times 8)2 \div 8) = 13$

$104((x - 24) \times 2 \div 8) = 13$

$104 \div \frac{( -x - 24) \times 2}{8} = 13$

$104 \div \frac{x - 24}{4} = 13$

$104 \times \frac{4}{x - 24} = 13$

$\frac{416}{x - 24} = 13$

$416 = 13(x - 24)$

$32 = x - 24$

$- x = - 24 - 32$

$- x = - 56$

$x = 56$