Zadanie 2.84Proszę pisać z obliczeniami :)Z góry dziękuję!.... Question from @Zipro

Zipro @Zipro

October 2018 1 23 Report

Zadanie 2.84

Proszę pisać z obliczeniami :)

Z góry dziękuję!

SyntiaxD

a) 2(x+4) + a = 0,5x + 9,5

2(5 + 4) + a = 0,5 · 5 + 9,5

2 · 9 + a = 2,5 + 9,5

18 + a = 12

a = - 6

b) (3x-4)(3x+a) = 9x² + 1

(3 · 7 - 4)(3 · 7 + a) = 9 · 7² + 1

(21 - 4)(21 + a) = 9 · 49 + 1

17(21 + a) = 442

357 + 17a = 442

17a = 85

a = 5

c) $\frac{2x}{x^2+9}=\frac{2x+a}{27} \\ \\ \frac{2\cdot3}{3^2+9}=\frac{2\cdot3+a}{27} \\ \\ \frac{6}{18}=\frac{6+a}{27} \\ \\ \frac{1}{3}=\frac{6+a}{27} \\ \\ 27=3(6+a) \\ 27 = 18 + 3a \\ 27 - 18 = 3a \\ 3a=9 \\ a=3$

d) $3-2x^3=\frac{x^2+a}{4} \\ \\ 3-2\cdot (-1)^3=\frac{(-1)^2+a}{4} \\ \\ 3-2=\frac{a+1}{4} \\ \\ 1=\frac{a+1}{4} \\ \\ 4=a+1\\ a=3$

e) (x-a)(2x+1)=(2x-a)(x+1)

(-1-a)(2 ·(-1) + 1) = (2 · (-1) - a)(-1+1)

-1(-1-a) = 0

1 + a = 0

a = -1

f) (3x + 1)(x + a) - 3(x - 1)(x - a) = 4

(3 · 0,5 + 1)(0,5 + a) - 3(0,5 - 1)(0,5 - a) = 4

2,5(0,5 + a) - 3 · (-0,5) · (0,5 - a) = 4

1,25 + 2,5a + 1,5(0,5 - a) = 4

1,25 + 2,5a + 0,75 - 1,5a = 4

a = 4 - 0,75 - 1,25

a = 2

g) g) 3(2x + a)(3x + 2) - 2(3x + 1)² = 43

3(2 · 1 + a)(3 · 1 + 2) - 2(3 · 1 + 1)² = 43

3(2 + a) · 5 - 2 · 4² = 43

15(2 + a) - 32 = 43

30 + 15a - 32 = 43

15a = 43 - 30 + 32

15a = 45

a = 3

h) $\frac{ax-5}{6}+\frac{x+a}{4}=\frac{5-ax}{3}-\frac{3a-7x}{4}-x \ / \cdot 12 \\ \\ 2(ax-5)+3(x+a)=4(5-ax)-3(3a-7x)-12x \\ 2(a-5)+3(a+1)=4(5-a)-3(3a-7)-12 \\ 2a-10+3a+3=20-4a-9a+21-12 \\ 18a=36 \\ a=2$