Question

qual o valor numérico das expressões algébricas?

a)x²-x+8 para x=2
b)x²-5x+8 para x= -2
c)x²+2xy para x= -4 e y=0
d)x²+2xy para x= -2 e y = -3
gente me ajuda :p

Answer 1

a) x^2-x+8
2^2-2+8
4-2+8
2+8=10
b) x^2-5x+8
(-2)^2-5.(-2)+8
4+10+8=22
c) x^2+2xy
(-4)^2+2.(-4).0
8-0=8
d) x^2+2xy
(-2)^2+2.(-2).(-3)
4+12=16

Answer 2

$a)x^{2}-x+8\\\\2^{2}-2+8\\\\4-2+8\\\\10\\\\b)x^{2}-5x+8\\\\-2^{2}-5.(-2)+8\\\\4+10+8\\\\22\\\\c)x^{2}+2xy\\\\-4^{2}+2.(-4).0\\\\16\\\\d)x^{2}+2xy\\\\-2^{2}+2.(-2).(-3)\\\\4+12\\\\16$