A) X – 11/15 = 3+x / 5 B) 1 + 1/2 + 1/4 + 1/8 + 1/16 + x × 5 = 3 29/08/2021 Bởi Anna A) X – 11/15 = 3+x / 5 B) 1 + 1/2 + 1/4 + 1/8 + 1/16 + x × 5 = 3
Đáp án: b, B = 1 + 1/2 + 1/4 + 1/8 + 1/16 + x × 5 = 3 Đặt A = 1 + 1/2 + 1/4 + 1/8 + 1/16 = 1 + 8/16 + 4/16 + 2/16 + 1/16 = 31/16 Thay A vào B ta đc B = 31/16 + x.5 = 3 => 5 . x = 3 – 31/16 = 17/16 => x = 17/16 : 5 = 17/80 a, x – 11/15 = 3+x / 5 => x = 3+x / 5 + 11/15 = 9 + 3x + 11/15 = 3x+20/15 => x = 3x+20/15 => 3x + 20 = 15x => 20 = 15x – 3x => 20 = 12x => x = 20 /12 = 5/3 Giải thích các bước giải: Bình luận
Đáp án: \(a,\ x=\dfrac{5}{3}\\ b,\ x=\dfrac{17}{80}\) Giải thích các bước giải: \(a,\ x-\dfrac{11}{15}=\dfrac{3+x}{5}\\ ⇔\dfrac{15x}{15}-\dfrac{11}{15}=\dfrac{3\times (3+x)}{15}\\ ⇔15x-11=3\times (3+x)\\ ⇔15x-11=9+3x\\⇔15x-3x=9+11\\ ⇔12x=20\\ ⇔x=\dfrac{20}{12}=\dfrac{5}{3}\\ \text{Vậy x = $\dfrac{5}{3}$}\\ b,\ 1+\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+x\times 5=3\\ ⇔x\times 5=3-\dfrac{1}{16}-\dfrac{1}{8}-\dfrac{1}{4}-\dfrac{1}{2}-1\\ ⇔x\times 5=\dfrac{48}{16}-\dfrac{1}{16}-\dfrac{2}{16}-\dfrac{4}{16}-\dfrac{8}{16}-\dfrac{16}{16}\\ ⇔x\times 5=\dfrac{48-1-2-4-8-16}{16}\\ ⇔x\times 5=\dfrac{17}{16}\\ ⇔x=\dfrac{17}{16}:5\\ ⇔x=\dfrac{17}{80}\\ \text{Vậy x = $\dfrac{17}{80}$}\) chúc em học tốt! Bình luận
Đáp án:
b, B = 1 + 1/2 + 1/4 + 1/8 + 1/16 + x × 5 = 3
Đặt A = 1 + 1/2 + 1/4 + 1/8 + 1/16
= 1 + 8/16 + 4/16 + 2/16 + 1/16 = 31/16
Thay A vào B ta đc
B = 31/16 + x.5 = 3
=> 5 . x = 3 – 31/16 = 17/16
=> x = 17/16 : 5 = 17/80
a, x – 11/15 = 3+x / 5
=> x = 3+x / 5 + 11/15 = 9 + 3x + 11/15 = 3x+20/15
=> x = 3x+20/15
=> 3x + 20 = 15x
=> 20 = 15x – 3x
=> 20 = 12x => x = 20 /12 = 5/3
Giải thích các bước giải:
Đáp án:
\(a,\ x=\dfrac{5}{3}\\ b,\ x=\dfrac{17}{80}\)
Giải thích các bước giải:
\(a,\ x-\dfrac{11}{15}=\dfrac{3+x}{5}\\ ⇔\dfrac{15x}{15}-\dfrac{11}{15}=\dfrac{3\times (3+x)}{15}\\ ⇔15x-11=3\times (3+x)\\ ⇔15x-11=9+3x\\⇔15x-3x=9+11\\ ⇔12x=20\\ ⇔x=\dfrac{20}{12}=\dfrac{5}{3}\\ \text{Vậy x = $\dfrac{5}{3}$}\\ b,\ 1+\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+x\times 5=3\\ ⇔x\times 5=3-\dfrac{1}{16}-\dfrac{1}{8}-\dfrac{1}{4}-\dfrac{1}{2}-1\\ ⇔x\times 5=\dfrac{48}{16}-\dfrac{1}{16}-\dfrac{2}{16}-\dfrac{4}{16}-\dfrac{8}{16}-\dfrac{16}{16}\\ ⇔x\times 5=\dfrac{48-1-2-4-8-16}{16}\\ ⇔x\times 5=\dfrac{17}{16}\\ ⇔x=\dfrac{17}{16}:5\\ ⇔x=\dfrac{17}{80}\\ \text{Vậy x = $\dfrac{17}{80}$}\)
chúc em học tốt!