Question

tìm số tự nhiên x biết:

a. 326 - 2x = 78

b. 42 . 5 - (3x + 6) = 3⁴

c. 4^x : 64 = 4²⁵⁰

d. (x + 1) + (x + 2) + (x + 3) +...+ (x + 29) + (x + 30) = 495

Answer 1

a) \(326-2x=78\Rightarrow2x=326-78=248\)

\(\Rightarrow x=248:2=124\)

b) \(42.5-\left(3x+6\right)=3^4\Rightarrow210-\left(3x+6\right)=81\)

\(\Rightarrow3x+6=210-81=129\Rightarrow3x=129-6=123\)

\(\Rightarrow x=123:3=41\)

Answer 2

a, 326 -2x =78

\(\Rightarrow\)2x=326-78=248

\(\Rightarrow\)x=248/2=124

b,\(42.5-\left(3x+6\right)=3^4\)

\(\Rightarrow\)\(210-3x-6=81\)

\(\Rightarrow\)3x=123

\(\Rightarrow\)x=123/3=41

c, \(4^x:64=4^{250}\)

\(\Rightarrow\)\(4^x:4^3=4^{250}\)

\(\Rightarrow\)x=253

d, \(30x+1+2+3+...+30=495\)

\(\Rightarrow\)\(30x+465=495\)

\(\Rightarrow\)\(x=1\)