Question

[Nguyen Tran Ngoc Diep]

Tim x

a.142.4^2-(7.5^2+4.x)=(4^3.157):4^2

b.[(7x+23):6^2-5^2]:29=18^2

Cac ban giup minh nha minh can ngay hom nay

Answer 1

[qwerty]

a) \(142\cdot4^2-\left(7\cdot5^2+4x\right)=\left(4^3\cdot157\right):4^2\)

\(\Leftrightarrow142\cdot16-\left(7\cdot25+4x\right)=\left(64\cdot157\right):16\)

\(\Leftrightarrow2272-\left(175+4x\right)=10048:16\)

\(\Leftrightarrow2272-145-4x=628\)

\(\Leftrightarrow2097-4x=628\)

\(\Leftrightarrow-4x=-1469\)

\(\Leftrightarrow x=\dfrac{1469}{4}\)

Vậy \(x=\dfrac{1469}{4}\)

b) \(\left[\left(7x+23\right):6^2-5^2\right]:29=18^2\)

\(\Leftrightarrow\left(\dfrac{7x+23}{6^2}-25\right)\cdot\dfrac{1}{29}=18\)

\(\Leftrightarrow\left(\dfrac{7x+23}{36}-25\right)\cdot\dfrac{1}{29}=18\)

\(\Leftrightarrow\dfrac{7x+23-900}{36}\cdot\dfrac{1}{29}=18\)

\(\Leftrightarrow\dfrac{7x-877}{36}\cdot\dfrac{1}{29}=18\)

\(\Leftrightarrow\dfrac{7x-877}{1044}=18\)

\(\Leftrightarrow7x-877=18792\)

\(\Leftrightarrow7x=18792+877\)

\(\Leftrightarrow7x=19669\)

\(\Leftrightarrow x=\dfrac{19669}{7}\)