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
Step-by-step explanation:
Use the Rational Zero Theorem to list all possible rational zeros of the function.
Use synthetic division to evaluate a given possible zero by synthetically dividing the candidate into the polynomial. ...
Repeat step two using the quotient found with synthetic division. ...
Find the zeros of the quadratic function.
All you have to do is divide the left side of the ratio by 5 and the right side of the ratio by 7. The one that comes out even on both sides is the correct one.
4.50+4.50=9.00=9
+
2.39+2.39=4.78
+
1.99
=
15.77
15.77-25=-9.23
