Answer:
-75
Step-by-step explanation:
f(x)=7x-5
f(-10)=7(-10)-5
f(-10)=-70-5
f(-10)=-75
1/5+1/7=12/35 of one room painted per hour
1 room/(12/35)=35/12 hours per room working together
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X + 5y = 1 . . . . (1)
8x - 2y = 3 . . . .(2)
Solution 1.
From (1), x = 1 - 5y
substituting for x in (2), we have:
8(1 - 5y) - 2y = 3
8 - 40y - 2y = 3
8 - 42y = 3
42y = 5
y = 5/42
x = 1 - 5(5/42) = 1 - 25/42 = 17/42.
Solution 2.
Multiply (1) by 8, to get:
8x + 40y = 8 . . . . . (3)
(3) - (2) = 40y - (-2y) = 8 - 3
42y = 5
y = 5/42
substitute for y into (3), to get:
8x + 40(5/42) = 8
8x + 100/21 = 8
8x = 8 - 100/21 = 68/21
x = (68/21)/8 = 17/42
We are given 2 points with there coordinates easy to calculate:
the upper one A(1,15) & the lower one B(6,10). Moreover the equation of this linear function is y = mx + b
1st) calculate m= (10-15) / (6-1) [FOMULA m=(y₂ - y₁) / (x₂ - x₁)]
m= -5/5 ==> m= - 1==> y=-x + b. To calculate b, replace x & y by any of the 2 points A, B. Say A(1,15)
15 = - (1) + b ==> b= 16 & final equation y = -x +16