Answer:
The 1st, 2nd and 5th options are correct.
Step-by-step explanation:
The equation of a line can be written in the form of y=mx+c, where m is the gradient and c is the y-intercept.
①Rewrite the given equation into the form of y=mx+c to find the gradient.
[tex]- \frac{5}{3} x = \frac{1}{4} y - 8 \\ \frac{1}{4} y = - \frac{5}{3} x + 8 \\ y = - \frac{20}{3} x + 32[/tex]
Thus, the gradient of the given equation is [tex] - \frac{20}{3} [/tex].
② Find gradient of unknown line.
The product of the gradients of perpendicular lines is -1.
Let m be the gradient of the unknown line.
[tex]- \frac{20}{3} m = - 1 \\ m = - 1 \div ( - \frac{20}{3} ) \\ m = - 1 \times ( - \frac{3}{20} ) \\ m = \frac{3}{20} [/tex]
③Substitute the value of m into the equation.
[tex]y = \frac{3}{20} x + c[/tex]
④ Find the value of c by substituting a pair of coordinates.
When x= -7, y= 3,
[tex]3 = \frac{3}{20} ( - 7) + c \\ 3 = - \frac{21}{20} + c \\ c = 3 + \frac{21}{20} \\ c = 4 \frac{1}{20}[/tex]
Thus, the equation of the line is [tex]y = \frac{3}{20} x + 4 \frac{1}{20} [/tex].
Thus, the 4th option is incorrect.
Writing c as an improper fraction,
[tex]y = \frac{3}{20}x + \frac{81}{20} [/tex]
Thus, the 1st option is correct.
-3 from both sides of the equation:
[tex]y - 3 = \frac{3}{20} x + \frac{21}{20} [/tex]
Factorise 3/20 out of the right hand side:
[tex]y - 3 = \frac{3}{20} (x + 7)[/tex]
Thus, the 2nd option is correct.
The 3rd option is incorrect as factorising -20/3 out would leave us with -0.0225 as the coefficient of x.
Let's look at the 5th option.
[tex]y = \frac{3}{20} x + 4 \frac{1}{20} [/tex]
×20 on both sides:
[tex]20y = 3x + 81[/tex]
-20y on both sides:
[tex]3x - 20y + 81 = 0[/tex]
-81 on both sides:
[tex]3x - 20y = - 81[/tex]
Thus, the 5th option is also correct.
