Question

Przekształć wyrażenia do najprostszej postaci i oblicz ich wartość liczbową .

Answer 1

Zad. 1

a = -5

-3a²-16(a/2-1) + 3( a²+2) *2*12,5 =  -3a² -8a + 16 +75 ( a² +2) =

=  -3a² -8a + 16 +75a² +150 = 72a² - 8a + 166

72a² - 8a + 166 = 72 * (-5)² -8* (-5) + 166 = 72*25 + 40 + 166 =

= 1800 + 40 + 166 = 2006

 

Zad.2

a = -1/2 ,  b= ½

1/4[4 – 3(b + 2a) ] – 2 (1/2b –a) = 1/4[ 4 – 3b – 6a] – b + 2a=

= 1 – 3/4b -6/4a – b + 2a = 1 – 1 ¾ b  + ½ a

=1 – 1 ¾ b  + ½ a= 1 – 1 ¾ * ½   + ½ * (-½)  = 1 – 7/4 *½  - ¼ =

= 1 – 7/8 – 2/8 = 1 – 9/8 = - 1/8

 

Zad.3

x = -1

4(0,2x + 2) –[2-4(0,5x-2)] : ( 1/4 : 0,75) = 0,8x +8 – ( 2 – 2x +8): ( 1/4: 75/100) =

0,8x +8 – ( 10-2x) : (1/4 * 100/75) = 0,8x +8 – ( 10-2x): 1/3 = 0,8x +8 - ( 10-2x) *3 =

= 0,8x +8 – 30 + 6x = 6,8x -24

6,8x -24 = 6,8 *(-1) -24 = -6,8 – 24 = - 30,8

 

Zad.4

x = 9

20% [ (1/3 x -5)² + 6x] = 2/10 [ 1/9x² - 2*1/3*5x + 25 + 6x] =

= 1/5[ 1/9x² - 10/3 *x + 25 + 6x] = 1/5 [1/9x² -3 1/3x +25 + 6x] =

= 1/5[1/9x² +  2 2/3x + 25] = 1/5 * 1/9 x² + 1/5 * 8/3 x + 1/5 * 25 =

= 1/45 x² + 8/15x + 5

 1/45 x² + 8/15x + 5 = 1/45* 9² + 8/15 * 9 + 5 = 1/45*81 + 24/5 + 5 =

= 9/5 + 24/5 + 5 = 1,8 + 4,8 +5 = 11,6 = 11 i 6/10 = 11 i 3/5