All the options are incorrect, if you're talking about circle! which is most common
C = 2πr..... It is the relation for Circle's if you're considering something else, then, please mention!
Substitution is where we first Isolate one of the unknowns, express it in terms of the other unknown, and replace the isolated unknown with the other unknown in another equation. So that each time we only need to deal with one unknown. I think you'll get a better idea here:
First name these 2 equations with 1 and 2.
4x + 5y = 7 (1)
y = 3x + 9 (2)
Since y is already isolated in (2), so we can skip the isolation step and continue to substitute.
Substitute (2) into (1).
4x + 5(3x+9) = 7
Expand.
4x + 15x + 45 = 7
Group.
19x + 45 = 7
Shift +45 to the other side and turn it into -45.
19x = 7 - 45
19x = -38
Shift x19 to the other side, turn it into /19.
X = - 38/19
X = - 2
Now we solved x already, we can just substitute x= - 2 back to equation (2).
y = 3(-2) + 9
y = - 6 + 9
y = 3
So, the answers are
x = - 2
y = 3
Equation describes a sloping line. For any
equation ax+by+c = 0, slope is .<span>X intercept is found by setting y to 0: ax+by=c becomes ax=c. that means that x = c/a. 30/5 = 6.Y intercept is found by setting x to 0: the equation becomes by=c, and therefore y = c/b. Y intercept is 30/-3 = -10.Slope is -5/-3 = 1.66666666666667.<span> Equation in slope-intercept form: y=1.66666666666667*x+-10.</span></span>
