Given the equations below, what is the value of \(\sqrt{\frac{a}{b}}\)?
a⁄2 = b + 1
3(a – b) = –21
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Solution
Solve the first equation for a in terms of b by multiplying both sides of the equation by 2. a = 2b + 2. Substitute this expression for a in the second equation:
3(2b + 2 – b) = –21
3(b + 2) = –21
3b + 6 = –21
3b = –27
b = –9
Substitute the value of b into the first equation and solve for a:
a⁄2 = –9 + 1
a⁄2 = –8
a = –16
Since a = –16 and b = –9, the value of \(\sqrt{\frac{a}{b}}=\sqrt{\frac{-16}{-9}}=\sqrt{\frac{16}{9}}=\frac{4}{3}\)
Given the equations below, what is the value of (y – x)2?
9(x – 1) = 2 – 4y
2y + 7x = 3
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Solution
First, simplify the first equation by multiplying (x – 1) by 9: 9(x – 1) = 9x – 9. Then, add 9 and 4y to both sides of the equation. The first equation becomes 9x + 4y = 11. Then, multiply the second equation by –2 and add it to the first equation. The y terms will drop out, and you can solve for x:
–2(2y + 7x = 3) = –4y – 14x = –6
x = –1
Substitute the value of x into the second equation and solve for y:
2y + 7(–1) = 3
2y – 7 = 3
2y = 10
y = 5
Since y = 5 and x = –1, the value of (y – x)2 = (5 – (–1))2 = 62 = 36.
Given the equations below, what is the value of (p + q)1⁄2?
8q + 15p = 26
–5p + 2q = 24
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Solution
Multiply the second equation by 3 and add it to the first equation. The p terms will drop out, and you can solve for q:
3(–5p + 2q = 24) = –15p + 6q = 72
q = 7
Substitute the value of q into the second equation and solve for p:
–5p + 2(7) = 24
–5p + 14 = 24
–5p = 10
p = –2
Since p = –2 and q = 7, the value of (p + q)2 = (–2 + 7)2 = 52 = 25.
Given the equations below, what is the value of x⁄y?
4x + 6 = –3y
–2x + 3 = y + 9
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Solution
First, simplify the second equation by subtracting 9 from both sides of the equation. The second equation becomes –2x – 6 = y. Then, multiply the equation by 2 and add it to the first equation. The x terms will drop out, and you can solve for y:
2(–2x – 6 = y) = –4x – 12 = 2y
y = 6
Substitute the value of y into the first equation and solve for x:
4x + 6 = –3(6)
4x + 6 = –18
4x = –24
x = –6
Since x = –6 and y = 6, the value of x⁄y = –6⁄6 = –1.
Given the equations below, what is the value of x – y?
\(\frac{x+y}{3}=8\)
2x – y = 9
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Solution
Solve the second equation for y in terms of x; 2x –y = 9, –y = –2x + 9, y = 2x – 9. Substitute this expression for y in the first equation and solve for x:
\(\frac{x+2x-9}{3}=9\)
\(\frac{3x-9}{3}=8\)
x – 3 = 8
x = 11
Substitute the value of x into the second equation and solve for y:
2(11) – y = 9
22 – y = 9
–y = –13
y = 13
Since x = 11 and y = 13, the value of x – y = 11 – 13 = –2.