+0

# 7^x+7^(x-2)+7(x+1)=7*393

0
390
2

$${{\mathtt{7}}}^{{\mathtt{x}}}{\mathtt{\,\small\textbf+\,}}{{\mathtt{7}}}^{\left({\mathtt{x}}{\mathtt{\,-\,}}{\mathtt{2}}\right)}{\mathtt{\,\small\textbf+\,}}{\mathtt{7}}{\mathtt{\,\times\,}}\left({\mathtt{x}}{\mathtt{\,\small\textbf+\,}}{\mathtt{1}}\right) = {\mathtt{7}}{\mathtt{\,\times\,}}{\mathtt{393}}$$

Aug 18, 2015

#1
+17747
+5

If the original problem were entered slightly incorrectly:

7x + 7(x - 2) + 7(x + 1)  =  7·393

7x + 7· 7-2 + 7x · 71  =  7·393

(1 + 7-2 + 7) · 7x  =  7·393

(1 + 1/49 + 7) · 7x  =  7·393

(393/49) · 7x  =  7·393

7x  = (7·393)·(49/393)

7x  = 7·49 = 73

x = 3

Aug 18, 2015

#1
+17747
+5

If the original problem were entered slightly incorrectly:

7x + 7(x - 2) + 7(x + 1)  =  7·393

7x + 7· 7-2 + 7x · 71  =  7·393

(1 + 7-2 + 7) · 7x  =  7·393

(1 + 1/49 + 7) · 7x  =  7·393

(393/49) · 7x  =  7·393

7x  = (7·393)·(49/393)

7x  = 7·49 = 73

x = 3

geno3141 Aug 18, 2015
#2
0

$${{\mathtt{7}}}^{{\mathtt{x}}}{\mathtt{\,\small\textbf+\,}}{{\mathtt{7}}}^{\left({\mathtt{x}}{\mathtt{\,-\,}}{\mathtt{2}}\right)}{\mathtt{\,\small\textbf+\,}}{\mathtt{7}}{\mathtt{\,\times\,}}\left({\mathtt{x}}{\mathtt{\,\small\textbf+\,}}{\mathtt{1}}\right) = {\mathtt{7}}{\mathtt{\,\times\,}}{\mathtt{393}} \Rightarrow {\mathtt{x}} = {\mathtt{\,-\,}}{\frac{\left({\mathtt{50}}{\mathtt{\,\times\,}}{{\mathtt{7}}}^{\left({\mathtt{x}}{\mathtt{\,-\,}}{\mathtt{2}}\right)}{\mathtt{\,-\,}}{\mathtt{2\,744}}\right)}{{\mathtt{7}}}}$$

Easy one and difficulty:normal

Aug 19, 2015