Answer:
(a)
Step-by-step explanation:
Note the expansion of (x - 5y)² is
(x - 5y)² = x² - 10xy + 25y² , that is
(x - 5y)² = x² + 25y² - 10xy ← substitute given values
(- 16)² = 416 - 10xy
256 = 416 - 10xy ( subtract 416 from both sides )
- 160 = - 10xy ( divide both sides by - 10 )
xy = 16 → (a)
Answer:
graph it
Step-by-step explanation:
<u>Answer</u>:
x = 7, y = 2
<u>Explanation</u>:
equations given:
x + 7y = 21
x + 4y = 15
make "x" the subject:
x + 7y = 21
x = 21 - 7y .........equation 1
x + 4y = 15
x = 15 - 4y .......equation 2
Solving both the equations simultaneously:
15 - 4y = 21 - 7y
-4y + 7y = 21 - 15
3y = 6
y = 6 ÷ 3
y = 2
If y is 2
Then x = 21 -7y;
x = 21 - 7(2)
x = 21 - 14
x = 7
I think it can be C. but then again who am i
