Question

Bài 1: Tìm X, biết:

( 1 +X ) + ( 2 + X) + (3 + X )+ (4 + X )+ (5 + X ) = 10 x 5

Answer 1

Đổi x thành a, ta có:

(1 + a) + ( 2 + a) + (3 + a) + ( 4 + a) + (5 + a) = 10 x 5

1 + a +  2 + a + 3 + a + 4 + a + 5 + a = 50

a + a + a + a + a + 1 + 2 + 3 + 4 + 5  = 50

a x 5 + 15                                         = 50

                                               a x 5  = 50 - 15

                                         a x 5        = 35

                                                  a    = 35 : 5

                                                    a  = 7

Answer 2

(1+X)+(2+X)+(3+x)+(4+x)+(5+x)=5 NHAN 10

1+X+3+X+2+X+4+X+5+X=50

X NHAN5+1+2+3+4+5=50

x NHAN 5+15=50

X NHAN5=50-15=35

X=35:5=7

Answer 3

\(\left(1+x\right)+\left(2+x\right)+\left(3+x\right)+\left(4+x\right)+\left(5+x\right)=5.10\)

\(\left(1+x\right)+\left(2+x\right)\left(3+x\right)+\left(4+x\right)+\left(5+x\right)=50\)

\(1+x+2+x+3+x+4+x+5+x=50\)

\(\left(x+x+x+x+x\right)-\left(1+2+3+4+5\right)=50\)

               5 số hạng x

              \(5x+15=50\)

              \(5x=50-15\)

              \(5x=35\Rightarrow x=7\)