b)7 –(2x + 4) = -(x + 4)
c)4(3x –2 ) –3( x –4 ) = 7x + 10
d)–x2–12x + 21 = (3 –x )(x + 11)
e)9x + 5×2 + 1 = 5×2–22 + 13x
help me plz
b)7 –(2x + 4) = -(x + 4)
c)4(3x –2 ) –3( x –4 ) = 7x + 10
d)–x2–12x + 21 = (3 –x )(x + 11)
e)9x + 5×2 + 1 = 5×2–22 + 13x
help me plz
Đáp án:
CHÚC BẠN HỌC TỐT!!!!!
Giải thích các bước giải:
b)7 –(2x + 4) = -(x + 4)
7 – 2x – 4 = -x – 4
-2x + 3 = -x – 4
-2x + x = -4 -3
x = 7.
c)4(3x –2 ) –3( x –4 ) = 7x + 10
12x – 8 – 3x + 12 = 7x+10
9x + 4 = 7x + 10
9x – 7x = 10 – 4
2x = 6
x = 3.
d)–x²–12x + 21 = (3 –x )(x + 11)
-x² – 12x + 21= -x² – 8x + 33
12x – 21 = 8x – 33
12x – 8x = -33 + 21
4x = -12
x = – 3.
e)9x + 5x² + 1 = 5x²–22 + 13x
9x + 1 = 13x – 22
9x – 13x = -22 -1
-4x = -23
x = 23/4.
Đáp án:
Giải thích các bước giải:
b) 7-2x-4=-x-4
3-2x=-x-4
-2x+x=-4-3
-x=-7
x=7
c) 12x-8-3x+12=7x+10
9x+4=7x+10
9x-7x=10-4
2x=6
x=3
d) -x^2-12x+21=3x+33-x^2-11x
-12x+21=3x+33-11x
-12x+21=-8x+33
-12+21+8x-33=0
-4x-12=0
x+3=0
x=-3
e) 9x+1=-22+13x
9x-13x=-22-1
-4x=-23
x= 23/4