Question

giúp mk giải bài toán này vs:

Giải phương trình:

a) 0,5(2y-1) - ( 0,5- 0,2y) + 1 = 0

b) 3(3x-1) + 2= 5(1-2x)-1

c) \(\dfrac { 3x-1} { 24}\)- \(\dfrac { 2x+6} {36}\)-1 = 0

d) \(\dfrac { 11a-4} { 7} - \dfrac{ a-9} { 2} = 5\)

Answer 1

a) 0,5(2y-1) - (0,5-0,2y) + 1 = 0

\(\Leftrightarrow\) y - 0,5 - 0,5 + 0,2y + 1 = 0

\(\Leftrightarrow\) 1,2y - 1 + 1 = 0

\(\Leftrightarrow\) 1,2y = 0

\(\Leftrightarrow\) y = \(\frac{0}{1,2}\)= 0

Vậy y = 0

b) 3(3x-1) + 2 = 5(1-2x) - 1

\(\Leftrightarrow\) 9x - 3 + 2 = 5 - 10x - 1

\(\Leftrightarrow\) 9x + 10x = 5 -1 + 3 -2

\(\Leftrightarrow\) 19x = 5

\(\Leftrightarrow\) x = \(\frac{5}{19}\)

Vậy x = \(\frac{5}{19}\)

c) \(\frac{3x-1}{24}\)- \(\frac{2x+6}{36}\)- 1 = 0

\(\Leftrightarrow\) 3(3x-1) - 2(2x+6) -1.72 = 0

\(\Leftrightarrow\) 9x - 3 - 4x - 12 - 72 = 0

\(\Leftrightarrow\) 5x - 87 = 0

\(\Leftrightarrow\) 5x = 87

\(\Leftrightarrow\) x = \(\frac{87}{5}\)

Vậy x = \(\frac{87}{5}\)

d) \(\frac{11a-4}{7}\)- \(\frac{a-9}{2}\)= 5

\(\Leftrightarrow\) 2(11a-4) - 7(a-9) = 5

\(\Leftrightarrow\) 22a -8 -7a +63 = 5

\(\Leftrightarrow\) 15a + 55 = 5

\(\Leftrightarrow\) 15a = 5 - 55 = -50

\(\Leftrightarrow\) a = \(\frac{-50}{15}\)= \(\frac{-10}{3}\)

Vậy a = \(\frac{-10}{3}\)có vẻ như bạn viết sai đề rồi !

Answer 2

a )

0,5(2y-1) - ( 0,5- 0,2y) + 1 = 0 <=> y-0,5 - 0,5+0.2y+1=0 <=> y+0,2y=0,5+0,5-1 <=>1,2y=0 <=> y=0 b) 3(3x-1) + 2= 5(1-2x)-1 <=> 9x-3+2=5-10x-1 <=> 9x+10x = 3-2+5-1 <=> 19x = 5 <=> x = 5/19

c) (3x−1)/24 ) - 2x+6/36 - 1 = 0

<=> 9x - 3-4x-12-72 =0

<=> 9x-4x = 3+12+72

<=> 5x = 87 => x = 17,4

d ) (11a-4)/7 -( a-9)/2=5

<=> (11a-4)2 - (a-9)7=5.14

<=> 22a-8 - 7a +63 = 70

<=> 22a-7a = 8-63+70

<=> 15a = 15

<=> a = 1

Answer 3

Sửa câu d bị nhầm

d) \(\frac{11a-4}{7}\)- \(\frac{a-9}{2}\)= 5

\(\Leftrightarrow\) 2(11a -4 ) -7(a-9) = 5.14

\(\Leftrightarrow\) 22a -8 -7a +63 = 70

\(\Leftrightarrow\) 22a-7a = 70+8-63

\(\Leftrightarrow\) 15a = 15

\(\Leftrightarrow\) a = \(\frac{15}{15}\) = 1

Vậy a =1