Question

Suatu persegi panjang,panjangnya (2x + 7) cm dan lebarnya (3x - 2) cm.Jika kelilingnya. 50cm,maka luasnya adalah....

kasi tau caranya juga yaaa..

Answer 1

K = 2 × (p +l)
50 = 2 × (2×+7 + 3×-2)
25 = (2×+7 + 3× -2)
25 = 5× + 5
25 -5= 5×
20 =5×
×= 20÷5
×=4

p = 2×+7 = 2(4)+7 =8+7 =15
l = 3×-2 = 3(4)-2= 12-2 =10

L = p x l
= 15 ×10
=150

Answer 2

K = 2( 2x + 7 ) + 2( 3x - 2 )
50 = 4x + 14 + 6x - 4
50 = 10x + 10
40 = 10x
x = 4

L = ( 2x + 7 ) ( 3x - 2 )
   = ( 2 x 4 + 7 ) ( 3 x 4 - 2 )
   =  15 x 10
   = 150 cm2