Question

tìm x 

a, (x - 1) \(\in\)BC_(4:5:6) và x<400

b,(x - 1) \(\in\)BC_(4:5:6)và x \(⋮\)7 và x <400

c,(x - 1 ) \(\in\)BC_(6:20:15) và x\(\le\)30

d, x + 2 )\(\in\)BC_(8:16:24) và x \(\le\)250

Answer 1

a

4 =2²

5 =5.1

6=2.3

\(\Rightarrow BCNN\left(4,5,6\right)=2^2.3.5=60\)

BC (4,5,6 ) = B (60) ={0 ;60;120,240,360,420,......}

x-1 = {1 :61;121:241;361;421 ;.......}

mà x <400

=> x = 361

Answer 2

d 

8=2³

16=2⁴

24=2³.3

=> BCNN(......) = 2⁴.3=48

BC (.....) B(48)={0,48,96,144,192,240,288,......}

x+2={-2;46;94;142;190;238;286;.....}

mà\(x\le250\)

=> x = 238 

.......