1. The document contains 4 word problems with algebraic solutions. 2. The first problem involves finding the unknown side length of a rectangular field given other dimensions. The second finds volumes using geometric formulas. 3. The third equalizes the volumes of two cones with different radii and heights. 4. The fourth determines the time one printer takes to print a book set given the total time for two printers.

1. 1. Diketahui:
Panjang lapangan tanah kosong
Luas lapangan tanah kosong
Luas lapangan yang direncanakan
Panjang lapangan yang direncanakan
Lebar lapangan yang direncanakan
Ditanya: Persamaan kuadrat = ...?
Jawab:
( 60 – x ) ( 30 – x )
= 1000
1800 – 60x – 30x + x2
= 1000
2 =0
1800 – 1000 – 60x – 30x + x
800 – 90x + x2
=0
x2 – 90x + 800
=0
x2 – 10x – 80x + 800
=0
x ( x – 10 ) – 80 ( x – 10 )
=0
( x – 80 ) ( x – 10 )
=0
x = 80 atau x
= 10
Panjang lapangan yang direncanakan:
=60 – x
=60 – x
=50m
Luas lapangan yang direncanakan:
=30 – x
=30 – 10
=20m
2. Diketahui :
Panjang seng
Luas seng
Luas alas balok
Palas balok
Luas alas balok
=50cm
=40cm
=200cm2
=50 – 2x
=40 – 2x
Ditanya:
a. Persamaan kuadrat
b. Volume tempat air
=…?
=…?
Jawab:
a. Persamaan kuadrat
( 50 – 2x )( 40 – 2x )=200
2000 – 100x – 80x – 4x2 =200
2000 – 200 – 100x – 80x + 4x2 =0
1800 – 180x + 4x2 = 0
4x2 – 180x + 1800 = 0
X2 – 45x + 450 = 0
X2 – 15x – 30x + 450 = 0
x ( x – 15 ) – 30 ( x – 15 ) = 0
( x – 30 ) ( x –15 ) = 0
= 60m
= 30m
= 1000m2
= 60 – x
= 30 – x

2. X = 30 atau x = 15
Panjang alas:
= 50 – x
=50 – 15
= 35cm
Luas alas:
= 40 – x
= 40 –15
= 25cm2
Tinggi:
=x
=15cm
b. V = p x l x t
= 35cm x 25cm x 15cm
= 13.125 cm3
3. Diketahui:
Tinggi kerucut = 3 cm
Rumus:
V = ⅓π r 2 . t
V1 = ⅓ π ( r + 24 ) 2 . t
V2 = ⅓ π . r 2 ( t + 24 )
Ditanya : r … ?
Jawab:
V1
⅓ π ( r + 24 ) 2 . t
( r + 24 ) 2 . t
( r + 24 ) 2 . 3
3 ( r 2 + 48 r + 24 2 )
3 r 2 + 3 . 48 r + 24 . 24
r 2 + 48 r + 24 . 24
0
0
0
0
0
=
=
=
=
=
=
=
=
=
=
=
=
V2
⅓ π . r t + 24 )
r 2 ( t + 24 )
r 2 ( 3 + 24 )
27 r 2
27 r 2
9r2
9 r 2 – r 2 – 48 r – 24 . 24
8 r 2 – 48 r – 576
r 2 – 6 r – 72
r 2 + 6 r – 12 r – 72
( r – 12 ) ( r + 6 )
2(
4. Diketahui:
Printer1 = x jam
Printer2 = x + 1 jam
t1 + t2
= 1,2 jam
Ditanya: waktu yang diperlukan printer1 untuk mencetak satu set buku … ?
Jawab:

3. x2+x
=
1,2 ( 2 x + 1 )
x2+x
=
2,4 x+ 1,2
x 2 + x – 2,4 x – 1,2
=
0
x 2 – 1,4 x – 1,2
=
0
10 x 2 – 14 x – 12
=
0
10 x 2 – 20 x + 6 x – 12 =
0
( 10 x + 6 ) ( x – 2 ) =
0
10 x = – 6
x=2
x = – 6/10
x = – 0,6
atau