\(x-15\cdot10+7=15\)

\(x-150+7=15\)

\(x-157=15\)

\(x=15+157\)

\(x=172\)

Giải

2 × 4 = 8

8 × 2 = 16

ok nhưng nhớ cho mình 1 k nha 

10 + 20 + 30 + 40 + 50 + 60 + 70 + 80 + 90

=(10 + 90) + (20 + 80) + (30 + 70) + (40 + 60) + 50

= 100 + 100 + 100 + 100 + 50

= 400 + 50

= 450

Tổng bằng:

1288+5234-335+2345=8522

Đáp số: 8522

199 + 230 = 429

$\sqrt{x^4-8x^2+16}=2-x$

$\mathrm{\backslash (\backslash Leftrightarrow\backslash sqrt\{\backslash left(x^2-4\backslash right)^2\}=2-x\backslash )}$

\(\Leftrightarrow x^2-4=2-x\)

\(\Leftrightarrow x^2+x-6=0\)

\(\Leftrightarrow x^2+3x-2x-6=0\)

\(\Leftrightarrow\left(x+3\right)\left(x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+3=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=2\end{matrix}\right.\)