Question

(-3a2 + 2a - 5 ) + (7 - 3a + 3a2) при a= -4,5 2x - y - (3-y + 2x) при x +3,875 , y = -4,5

Answer 1

1. -a +2= 4.5+2= 6.5
2. 2x -y -3+y-2x= -3

Answer 2

Let's calculate the given expressions step by step:

Expression 1: (-3a^2 + 2a - 5) + (7 - 3a + 3a^2)

Substituting a = -4.5:

= (-3(-4.5)^2 + 2(-4.5) - 5) + (7 - 3(-4.5) + 3(-4.5)^2)

= (-3(20.25) - 9 - 5) + (7 + 13.5 + 61.875)

= (-60.75 - 9 - 5) + (7 + 13.5 + 61.875)

= (-74.75) + (82.375)

= 7.625

Therefore, when a = -4.5, the value of the expression (-3a^2 + 2a - 5) + (7 - 3a + 3a^2) is 7.625.

Expression 2: 2x - y - (3 - y + 2x)

Substituting x = 3.875 and y = -4.5:

= 2(3.875) - (-4.5) - (3 - (-4.5) + 2(3.875))

= 7.75 + 4.5 - (3 + 4.5 + 7.75)

= 12.25 - 15.25

= -3

Therefore, when x = 3.875 and y = -4.5, the value of the expression 2x - y - (3 - y + 2x) is -3.