\(\frac{1}{2}\times10+9=\hept{\begin{cases}?\\+\\5\end{cases}}\)

\(\frac{1}{2}+\frac{1}{2}+56+9+1\hept{\begin{cases}?\\+\\12\end{cases}}\)

\(\frac{1}{2}+\frac{1}{2}\times3+9\hept{\begin{cases}?\\+\\6\end{cases}}\)

\(\frac{1}{2}\times6+67\hept{\begin{cases}?\\+\\13\end{cases}}\)

\(\frac{1}{2}+\frac{1}{2}\times8+7\hept{\begin{cases}?\\+\\6\end{cases}}\)

5 BÀI TOÁN NHÉ!

\(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}-\frac{9}{a+b+c}=0\)

\(\frac{bc}{abc}+\frac{ac}{bca}+\frac{ab}{cab}-\frac{9abc}{\left(a+b+c\right)abc}=0\)

\(\left(A+b+c\right)bc+\left(a+b+c\right)ac+\left(a+b+c\right)ab-9abc=0\)

\(b^2c+c^2b+abc+a^2c+c^2a+abc+a^2b+b^2a+abc-9abc=0\)

\(b^2c+c^2b+a^2c+c^2a+a^2b+b^2a-6abc=0\)

\(c\left(b^2+a^2\right)+b\left(c^2+a^2\right)+a\left(c^2+b^2\right)-6abc=0\)

\(c\left(b^2+a^2-2ab\right)+b\left(c^2-2ac+a^2\right)+a\left(c^2+2cb+b^2\right)=0\)

\(c\left(b-a\right)^2+b\left(c-a\right)^2+a\left(c-b\right)^2=0\)

\(\)

1.Đúng ghi Đ, sai ghi S:

a)16:2=6;  b)10:2=5;  c)8:2  =4;  d)18:2=9;

e)20:2=3;  g)4:2  =2;  h)12:2=7;  i)2:2   =8.

2.Hoàn thành vào bảng sau:

3.Tìm x, biết:

a)\(2\times x=8\)   ; b)\(2\times x=12\)   ; c)\(2\times x=18\);

d)\(x\times8=16\); e)\(x\times10=20\); g)\(x\times x=4\).