Solve the system by substitution. {:[8x=y],[-9x+2y=21]:} (◻,◻)

Isolate y: Solve the first equation for y. Given 8x = y, we can see that y is already isolated. y = 8xSubstitute y into second equation: Substitute y = 8x into the second equation. The second equation is -9x + 2y = 21. Replace y with 8x. -9x + 2(8x) = 21Solve for x: Solve for x. -9x + 16x = 21 7x = 21 Divide both sides by 7 to find x. x = 21 / 7 x = 3Substitute x back into first equation: Substitute x = 3 back into the first equation to find y. y = 8x y = 8(3) y = 24

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Solve the system by substitution.

{:[8x=y],[-9x+2y=21]:}

(◻,◻)

Solve the system by substitution. $\newline$ $\begin{aligned} 8 x & =y \\ -9 x+2 y & =21 \end{aligned}$ $\newline$ $(\square, \square)$

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Algebra 2

Solve a system of equations in three variables using substitution

Full solution

Q. Solve the system by substitution.

\newline

\begin{aligned} 8 x & =y \\ -9 x+2 y & =21 \end{aligned}

\newline

(\square, \square)

Isolate $y$ : Solve the first equation for $y$ . $\newline$ Given $8x = y$ , we can see that $y$ is already isolated. $\newline$ $y = 8x$
Substitute $y$ into second equation: Substitute $y = 8x$ into the second equation. $\newline$ The second equation is $-9x + 2y = 21$ . Replace $y$ with $8x$ . $\newline$ $-9x + 2(8x) = 21$
Solve for x: Solve for x. $\newline$ $-9x + 16x = 21$ $\newline$ $7x = 21$ $\newline$ Divide both sides by $7$ to find x. $\newline$ $x = \frac{21}{7}$ $\newline$ $x = 3$
Substitute $x$ back into first equation: Substitute $x = 3$ back into the first equation to find $y$ . $\newline$ $y = 8x$ $\newline$ $y = 8(3)$ $\newline$ $y = 24$