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just olya [345]

2 years ago

6

Solve 3x+2y=7 and x-4y=-21 by using substitution

1 answer:

noname [10]2 years ago

7 0

$3x+2y=7 \\
x-4y=-21 \\ \\
\hbox{solve the second equation for x:} \\
x-4y=-21 \\
x=4y-21 \\ \\
\hbox{substitute 4y-21 for x in the first equation:} \\
3(4y-21)+2y=7 \\
12y-63+2y=7 \\
14y=7+63 \\
14y=70 \\
y=\frac{70}{14} \\
y=5 \\ \\
x=4y-21=4 \times 5-21=20-21=-1 \\ \\
\boxed{(x,y)=(-1,5)}$

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Section 5.2 Problem 17:

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2 years ago

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A.10 < 9, not true 10 is greater than 9

B. 9 < 10, true 9 is less than 10

C. 10 > 9, true 10 is greater than 9

D. 9 (is less than or equal to ) 10 true 9 is less than or equal to 10

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3 years ago