• Oct 19th 2006, 02:18 PM
sjallim
3x+3/4-2(x-5)=30

(2X*2X)-12X+9=0 USE FACTORISATION

(3X*3X)+13X+2=0 STATE ANSWER TO THREE SIGNIFICANT NUMBERS

X/8+3X/16=5/X

(X*X)-2X-6=0
• Oct 19th 2006, 02:53 PM
OReilly
Quote:

Originally Posted by sjallim
3x+3/4-2(x-5)=30

(2X*2X)-12X+9=0 USE FACTORISATION

(3X*3X)+13X+2=0 STATE ANSWER TO THREE SIGNIFICANT NUMBERS

X/8+3X/16=5/X

(X*X)-2X-6=0

1)
$\begin{array}{l}
3x + \frac{3}{4} - 2(x - 5) = 30 \\
3x + \frac{3}{4} - 2x + 10 = 30 \\
x = 20 - \frac{3}{4} \\
x = \frac{{77}}{4} \\
\end{array}
$

2)
$\begin{array}{l}
(2x*2x) - 12x + 9 = 0 \\
4x^2 - 12x + 9 = 0 \\
(2x - 3)^2 = 0 \\
\\
2x - 3 = 0 \\
2x = 3 \\
x = \frac{3}{2} \\
\end{array}
$

3)
$\begin{array}{l}
(3x*3x) + 13x + 2 = 0 \\
9x^2 + 13x + 2 = 0 \\
x_{1/2} = \frac{{ - 13 \pm \sqrt {97} }}{{18}} \\
\end{array}
$

4)
$\begin{array}{l}
\frac{x}{8} + \frac{{3x}}{{16}} = \frac{5}{x} \\
\frac{{2x + 3x}}{{16}} = \frac{5}{x} \\
\frac{{5x}}{{16}} = \frac{5}{x} \\
5x^2 = 80 \\
x^2 = 16 \\
x = \sqrt {16} \\
x = 4 \\
\end{array}
$

5)
$\begin{array}{l}
(x*x) - 2x - 6 = 0 \\
x^2 - 2x - 6 = 0 \\
x_{1/2} = \frac{{2 \pm \sqrt {4 + 24} }}{2} = \frac{{2 \pm \sqrt {28} }}{2} \\
\end{array}
$

I didn't calculate 3) and 5), hopefully you can do that.