1)
If \((2x+3y)(3y+2x)=z\), according to the given information, and \(x=3.2\) and \(z=457.96\), just plug those values in to solve for y:
\((2x+3y)(3y+2x)=z\) | Plug in the appropriate values for the given variables of x and z. | ||
\((2*3.2+3y)(2*3.2+3y)=457.96\) | Simplify what is inside the parentheses first. | ||
\((6.4+3y)(6.4+3y)=457.96\) | You might notice that both the multiplicand and multiplier are the same, which means that we can make this equation a tad simpler. | ||
\((6.4+3y)^2=457.96\) | Take the square root of both sides. Of course, this breaks the equation up into its positive and negative answer. | ||
\(6.4+3y=\pm\sqrt{457.96}\) | Although it may not be obvious, the square root of happens to work out nicely. | ||
\(6.4+3y=\pm21.4\) | To solve for y, we must break up the equation. | ||
| Now, subtract by 6.4 in both equations. | ||
| Divide by 3 on both sides. | ||
| Both of these y-values satisfy the equation, and these are the solutions. | ||
2)
This is a system of equations. I usually refrain from using the elimination method here because it is difficult to showcase. Therefore, I will use the substitution method.
I will solve for y in equation 2:
\(-2x-3y=2\) | Add 2x to both sides. |
\(-3y=2x+2\) | Divide by -3 to isolate y. |
\(y=-\frac{2x+2}{3}\) | |
Plug this value for y into equation 1 and then solve for x.
\(3x+5y=-2\) | Plug in the value for y that was determined from the previous equation. |
\(3x+5*\frac{2x+2}{-3}=-2\) | Do the multiplication first to simplify this monstrosity. |
\(5*\frac{2x+2}{-3}=\frac{5(2x+2)}{-3}=\frac{10x+10}{-3}\) | Now, reinsert this back into the original equation. |
\(3x+\frac{10x+10}{-3}=-2\) | Multiply by -3 on all sides to get rid of the fraction. |
\(-9x+10x+10=6\) | Combine the like terms on the left hand side. |
\(x+10=6\) | Subtract 10 on both sides. |
\(x=-4\) | |
Now, plug x=-4 into either equation and solve for y. I'll choose equation 2 because it look easier to do:
\(-2x-3y=2\) | Substitute all x's for -4. |
\(-2*-4-3y=2\) | |
\(8-3y=2\) | Subtract by 8 on both sides. |
\(-3y=-6\) | Divide by -3 to isolate y. |
\(y=2\) | |
Therefore, the coordinate where both lines intersect is \((-4,2)\).