I'd really appreciate some help on these questions, I'm really struggling
1 answer:
We can use linear combinations of the equations to eliminate variables.
3x - 4y = 1
-2x + 3y = 1
To eliminate y we'll make the linear combination of 3 times the first equation minus four times the second.
9x - 12y = 3
-8x + 12y = 4
Adding,
x = 7
We could solve for y directly but let's use another linear combination, twice the first plus three times the second:
2(3x - 4y) + 3(-2x + 3y)= 2(1)+3(1)
y = 5
Check: 3(7)-4(5)=1 good. -2(7)+3(5)=1 good.
Q18 Answer: (7,5)
y = -3x + 5
5x - 4y = -3
4y +1(5x - 4y) = 4(-3x + 5) + 1(-3)
5x = -12x + 20 -3
17 x = 17
x = 1
y = -3(1) + 5 = 2
Check: 5(1) - 4(2) = -3 good
Q19 Answer (1,2)
6x + 5y = 25
x = 2y + 24
6x = 12y + 144
5y = 25 - 12y - 144
17y = -119
y = -119/17= -7
x = 2y+24= 10
Check: 6(10)+5(-7)=25 good 2y+24=2(-7)+24=10=x good
Q20 Answer (10,-7)
3x + y = 18
-7x + 3y = -10
9x + 3y = 54
9x - -7x = 54 - -10
16x = 64
x=4
y = 18 -3x = 18-12=6
Check: 3(4)+6=18 good, -7(4)+3(6)=-10 good
Q21 Answer: (4,6)
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Answer:
16
Step-by-step explanation:
because 7 times 4 is 28
4 times 4 is 16.
also it says 1/4 and yeah the little box is 1/4 of the big one so that is your answer <3 :]
What is the total amount of money he owes back?
Answer:
C
Step-by-step explanation:
The big triangle and small triangles are similar so their corresponding sides are in proportion.
x/15 = 15/9
x= 15*15/9
x=25
Answer:
2 : 3
Step-by-step explanation:
bananas to apples = 8 : 12
simplify by dividing both values by highest common factor of 4:
8 ÷ 4 : 12 ÷ 4 = 2 : 3
Answer: 6cups of flour
Step-by-step explanation:
3cups of sugar to 2cups of flour
9cups of sugar to xcups of flour
Let sugar rep s
Flour rep f
So we have;
3s=2f
9s= xf
Cross multiply
3s×xf=2f×9s
Xf=2f×9s/3s
Xf=6f
Therefore, 9cups of sugar will be to 6cups of flour